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The Star Castle, St Mary's

A Scheduled Monument in St. Mary's, Isles of Scilly

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Latitude: 49.9154 / 49°54'55"N

Longitude: -6.321 / 6°19'15"W

OS Eastings: 89918.60658

OS Northings: 10640.778931

OS Grid: SV899106

Mapcode National: GBR BXSX.1H6

Mapcode Global: VGYC4.DD56

Entry Name: The Star Castle, St Mary's

Scheduled Date: 4 March 1997

Source: Historic England

Source ID: 1015671

English Heritage Legacy ID: 15486

County: Isles of Scilly

Civil Parish: St. Mary's

Traditional County: Cornwall

Lieutenancy Area (Ceremonial County): Cornwall

Church of England Parish: Isles of Scilly

Church of England Diocese: Truro


The monument includes a late 16th century artillery fort, the Star Castle,
built behind the northern crest of the Garrison, a large headland linked by an
isthmus to the south west coast of St Mary's in the Isles of Scilly. The Star
Castle is a Grade I Listed Building. This scheduling is divided into two
separate constraint areas.
The Star Castle contains a two-storey central house separated by a narrow
passage from an encircling rampart faced by walling; the rampart's outer face
forms an eight-pointed star in plan, giving the name of the fort. A covered
entrance passage passes through the rampart on the north east. Outside the
rampart a broad ditch is crossed by a stone causeway from the rampart
entrance. Beyond the ditch are remains of an outermost rampart.
The central house, excluded from this scheduling as detailed below, contained
a hall, accommodation and service areas in the fort's original layout. It is
nearly square in plan with sides oriented almost to the cardinal points and an
angled projection rising up the centre of each wall. Its main door opens to
the passage on the south of the east wall, with a service door opposite in the
west wall. A first floor door in the west wall opens to a bridge across the
passage to the rampart surface.
The open passage around the central house is c.2m wide, largely cobbled with
midline flagstones linking the main door of the house to the rampart entrance.
Steps rise to the rampart surface at the south east and north west corners.
On the north east, the open passage extends to a narrow covered entrance
passage dog-legged through the rampart and ending at a square-headed stone
doorway projecting slightly from the rampart. The doorway's moulded frame has
low relief initials at the base of each jamb: on the right, `FG' of Sir
Francis Godolphin, the islands' Governor when the fort was built; on the left,
`RA' of Richard Adams, the fort's architect. The lintel bears the date `1593'
and over the doorway, the outer face of an upper room includes a plaque
bearing the initials `ER' of Elizabeth I. The dog-leg of the passage's east
wall contains a deeply recessed square window, now blocked, directly facing
the doorway from an eastern guardhouse behind. The inner end of the entrance
passage was protected by a portcullis, evident from its wall slots, threshold
recessed for four vertical bars and a chamfered outer arch. A stepped masonry
structure above the slot's inner face carried the chains and winding gear for
raising the portcullis.
Several structures were built into the fabric of the rampart, opening off the
passage around the house. These include a guardhouse to each side of the
entrance passage at its inner end; the eastern has a blocked doorway in the
rampart inner wall. The western guardhouse, an addition of c.AD 1700, is
square with a pyramidal roof rising above the rampart surface. In its north
west corner is a blocked opening to a tunnel under the northern rampart,
joining a second tunnel on an angled course from a doorway at the centre of
the passage's north side to a blocked doorway in the rampart's outer wall
facing the ditch. These tunnels formed a sally port, intended to provide an
alternative means of exit in times of siege.
Other structures off the open passage include rooms forming service areas and
stores beneath the centre of the west and south ramparts. That on the west is
set back behind an open-fronted overhang in which the rampart's inner edge is
supported by granite beams and props; the room has a blocked door and window
facing the overhang. The room under the south rampart is subtriangular with a
single doorway and small square window facing the passage. A third small room
extends west from the south west corner of the passage.
The rampart rises 2.6m from the passageway to a flattened upper surface,
generally 6m-7m wide and almost level with the first floor of the central
house. It is faced internally and externally by walls of irregular granite
rubble, with more regular dressed slabs along most outer corners and with
dressed and usually chamfered jambs, lintels and sills at openings. The inner
wall ends as a low kerb along much of the rampart edge but at the four main
corners it rises as a parapet with musket slits covering the open passage. The
rampart's outer wall has a very steep slope, called a batter, over its lower
levels towards the ditch, becoming vertical towards the top and projecting as
a parapet over most of the rampart surface. Much of this parapet has an inner
ledge beneath a row of musket slits but at each internal corner this is
replaced by the blocking wall of a former gun embrasure, that on the NNE
retaining its original paved platform.
Each of the rampart's cardinal point corners contains a square building which
formed barracks for the castle garrison, that on the north described in 1715
as the `Gunners Barrack' and that on the west extended by a later porch. On
the rampart's south east corner is a small masonry sentry box; on the south
west corner is a roofless and partly re-built masonry latrine chamber. In the
north west corner is a flag platform, a level paved surface slightly higher
than the parapet top and reached by stone steps on the east. A flagstaff is
mounted against the south side of the platform. Built by 1715, this platform
is later than the original parapet.
In the north east corner, the room over the entrance doorway rises above the
rampart surface as a small square building described in 1715 as the `Gunners
Store'. Beside this room, the apex of the corner is occupied by a bellcote
with masonry piers and a rounded arch, raised above the parapet on a small
platform with access steps to the south.
The rampart's outer wall descends into the inner side of the ditch, resting on
bedrock in parts of the northern sector though its base is largely masked
elsewhere by surface deposits. The ditch is c.5m wide and up to 3m deep, cut
through the subsoil and, where exposed, into the bedrock. The base of the
ditch is masked by deep silt deposits, confirmed during modern cable-laying
operations. On the north east, a masonry causeway crosses the ditch from the
doorway in the rampart face; it has vertical side walls, rising to a parapet
whose inner ledges flank a cobbled surface with midline flags. At its outer
end is a pyramidal flight of seven visible stone steps to a modern metalled
drive beyond.
Beyond the outer lip of the ditch, an earthen outer bank extends around much
of the fort, though modern development and landscaping has levelled it on the
south. The bank's profile varies but where clear of modern scrub it is
generally c.7.5m wide and 1m high with a flattened top; a row of revetment
blocks are visible along its inner edge adjoining the ditch on the west of the
fort. A plan dated 1715 shows the bank gently merging with the natural slope
beyond, a form called a glacis. On the north it is modified by the levelling
cut for a modern road and by a modern levelled and revetted drive to the
fort's entrance steps. The bank widens to give a raised flattened area north
of the fort's flag platform, a feature considered to reflect the buried
foundations of a former gun room recorded at this location on early 18th
century plans.
The scheduling also includes a cobbled hollow 32m beyond the SSW side of the
fort's ditch and identified as one of several dewponds built in the mid 18th
century to improve the fort's water supply. The hollow is ovoid, 9.8m
north-south by 8.5m east-west, with sides sloping c.0.5m to a flattened base.
Its surface is neatly lined by cobbles, c.0.1m across, with a kerb of larger
slabs, c.0.3m across, on at least its north eastern periphery.
The physical remains of this artillery fort are complemented by a wealth of
historical sources regarding its construction, operation and context. The Star
Castle was built in 1593-4 as the first part of a major upgrading and
re-orientation of the islands' defences authorised by Elizabeth I to counter
continued threats and raids from Spain following the failure of the Armada in
1588. Its construction was quickly followed, from c.1600, by a bastioned
curtain wall to the east along the slope to the isthmus, creating a fortified
headland whose defensive system was successively extended and strengthened
over the next three centuries, during much of which the Star Castle remained
the controlling element. In March to April 1646 the Prince of Wales, later
Charles II, took refuge at the Star Castle during the Civil War; after 1648
the Star Castle became the last focus of Royalist resistance in England,
surrendering in 1651. The Star Castle also served as a prison for several
notable critics of the Government in the mid and later 17th century. In c.1700
extensive alterations took place, largely within the central house, and from
1834 the fort became the home of the Steward of the islands' lessee, Augustus
Smith. During World War I, the fort housed army officers. With increased
tourism on the islands the fort was converted to hotel use in 1933, most
modification again involving the central house. In World War II, the fort was
used to billet soldiers, with a signalling point on the roof of the central
The central house, the modern garage by the causeway, all modern fixtures and
fittings including the modern internal decoration of the rampart barracks,
modern garden furniture, all modern stored materials, all modern service pipes
and cables together with their fittings, existing trenches and supports are
excluded from the scheduling. Also excluded from the scheduling is the modern
metalled surface of the approach. The ground beneath all of these features is

The site of the monument is shown on the attached map extract.
It includes a 2 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.

Source: Historic England

Reasons for Scheduling

In the later 15th century, the need to deploy and counter increasingly
effective artillery began to revolutionise English fortification design. The
medieval castle, a tower and curtain wall defence, evolved into the artillery
castle, a strong stone defensive structure designed specifically to house
heavy guns in gun towers, with limited garrison accommodation and sometimes
accompanied by earthwork defences. They were usually sited to protect a
harbour entrance, anchorage, town or similar feature. Artillery castles
received their fullest expression in Henry VIII's maritime defence programme
between 1539 and 1545 when they were deployed at strategic points along the
east and south coasts of England. By then however new ideas developed in Italy
were producing fundamental changes that came to dominate artillery defence
design for the following three centuries. Low-lying earthen ramparts, faced by
stone or brick and fronting a ditch, more effectively absorbed artillery fire
while providing a platform for defensive artillery. Projecting angled bastions
allowed defensive fire across all flanks and lines of approach. The new
concepts proved highly adaptable, capable of application in the later 16th
century to large scale defensive circuits around major towns or for creating
smaller discrete fortifications.
The 16th century fortifications on the Isles of Scilly illustrate these
developments. On Tresco, the mid 16th century King Charles' Castle was one of
the last artillery castles to be built, with its tower pierced by tiers of gun
ports. The same defensive phase produced Harry's Walls on St Mary's, the
earliest English artillery fort to deploy true angle bastions, though
unfinished due to an inadequate site. When Government attention returned to
the defence of the islands after the Spanish Armada of 1588, the new concepts
in artillery defence were well-accepted and deployed on St Mary's at the Star
Castle, an unusually small artillery fort employing a stone-faced earthen
rampart; its size rendered it more appropriate to reduce the angle bastions to
an overall star plan, an adaptation recommended in several contemporary
military textbooks.
The Star Castle survives well and, in conjunction with the complementary early
phase of bastioned curtain wall crossing the Garrison neck, it forms one of
less than ten recorded fortifications of the Elizabethan period surviving
nationally. It was designed by one of the leading English military architects
of the time, Richard Adams, and demonstrates clearly the concepts of artillery
defence current in late 16th century England. The development of those
concepts is well-displayed in an unusually close grouping by the presence of
the King Charles' Castle on Tresco and the Harry's Walls fort on St Mary's.
The importance of the Star Castle in the study of fortifications is further
enhanced by its varied and evolving role as an integral part of the wider
system of defences on the Garrison headland from the early 17th century
onwards. The eventual domination of administrative and later non-military
functions illustrates the impact of developing military strategies and
technology on such fortifications, and some of the alternative uses which post
medieval societies have deemed appropriate for such imposing structures.

Source: Historic England


Books and journals
Adams, F, Adams, P, Star Castle and its Garrison, (1984)
Adams, F, Adams, P, Star Castle and its Garrison, (1984)
Saunders, A D, Fortress Britain, (1989)
Keystone Historic Buildings Consultants, Star Castle, St Mary's, Isles of Scilly, 1993, Unpubl report for EH; espec pp 45, 71
Keystone Historic Buildings Consultants, Star Castle, St Mary's, Isles of Scilly, 1993, Unpublished report for EH
p55; 1358-0/3/85; Star Castle Hotel, DNH, List of Buildings of Special Architectural or Historic Interest, (1992)
Parkes, C/CAU, Scilly SMR entries for PRN 7902 series, (1994)
Parkes, C/CAU, Scilly SMR entry PRN 7902.06 (formerly PRN 7654 pre-1994 revisn), (1994)
Saunders, A, Recent Fortifications and Defences Works Assessment, 1993, Unpubl report for English Heritage
Title: 1:2500 Ordnance Survey Map, SV 8715
Source Date: 1980

Title: 1:2500 Ordnance Survey Map; SV 8910
Source Date: 1980

Young, A/CAU, Cable Laying Operations at the Star Castle, Isles of Scilly, 1993, Unpubl CAU watching brief report

Source: Historic England

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