Monument MPM443 - THE SQUARE TOWER

The Square Tower was built in c1494 and formed part of the seaward defences to the town of Portsmouth. It was used as the military Governor's residence until c1580. The building has had many uses during its long history including as an artillery platform, magazine, semaphore station and meat store. The tower was restored between 1979 and 1986.

A keep-like structure built in c1494, the Square Tower has had many uses including as an artillery platform, Governor's residence, magazine, semaphore station and meat store. The tower was constructed using Bembridge limestone, but the interior of the building has been lined with red-brick since Tudor times, and is the earliest known brick-built structure in Portsmouth. The exterior walls were refaced with Portland stone in 1827.

The tower measures 19.96m x 19.94m and is 7.6m high on its north-east side. There are four floors which consist of a basement, ground floor, first floor and second floor (roof). The interior is divided in two by a red-brick spine wall built on a north-west south-east alignment, which supports two bays of barrel-vaulting. These features date to when the tower was converted for use as a meat store in the late-18th century. The tower has been extensively modified on a number of occasions throughout its history, and many of the original Tudor features have been destroyed. However, an archaeological survey conducted in the 1980s revealed that many interesting and important features have survived, some of which date to the 16th century. These include walls, windows and fireplaces. These features were exposed during a major restoration project undertaken between 1979 and 1986 (see below).

The bust of Charles I which occupies a niche on the north-east wall of the tower is a fibreglass replica of a gilded lead bust made around 1660 now held by Portsmouth Museum Service. The c1660 bust was a replacement for an original by Hubrecht le Sueur presented to the town by the King in 1635 to commemorate the monarch's safe return from a trip to Spain in 1623 when Prince of Wales. This original bust was destroyed during the Civil War.

Historical Background
Built in c1494 the Square Tower formed part of the seaward defences to the town of Portsmouth. It originally served the functions of artillery platform and residence to the military Governor of Portsmouth. In c1580 the Governor moved to a new residence which incorporated the remains of the Medieval Domus Dei (see MPM4) and the tower was converted for use as the garrison gunpowder magazine during the late-16th/early-17th century. It continued to be used as the town magazine until the 18th century.

The interior of the building was extensively modified in the 18th century, including the construction of a central spine-wall, the addition of barrel-vaulting at first floor ceiling level and the infilling of the basement. This work was carried out as one single phase and was originally thought to have taken place in c.1779 when the tower was converted for use as a meat store. However, further archaeological analysis carried out as part of monitoring works in 2024 [see below] dated the first floor timbers in the north-eastern part of the tower to 1734/5, suggesting the alterations were carried out in 1735 or shortly after, not in c.1779 as had been previously thought. It has been suggested that these alterations may be evidence that improvements were carried out to the building following a report written in 1716 that pointed out the defects of the powder store. The tower later became a victualling store around 1779. [4]

A semaphore signalling station was erected on top of the tower in 1823. This consisted of a tall wooden structure accessed from Ten-Gun Battery via an enclosed stairway. The semaphore was used to communicate with ships in the harbour and formed part of a chain of stations passing messages to and from London and the admiralty in Portsmouth. The semaphore was demolished in 1848 when the electric telegraph was introduced, and no trace of the structure survives.

In 1827 the exterior of the tower was refaced with Portland stone. During the mid-19th century the towers function reverted to that of a defensive position and it was placed under the jurisdiction of the Board of Ordnance. Concrete was used to reinforce the top of the building in order to accommodate three 8-inch guns on the south-west side, and an expense magazine was constructed in the south-east wall. When the town defences became redundant during the late-19th century the tower was used as a store. In 1940 a reinforced concrete first floor was added, red-brick subdividing walls constructed in the western half of the tower and a reinforced-concrete structure was erected at the west corner of the roof area. These features were removed during restoration work (see below). Prior to restoration the Sea Scouts had been based on the ground floor of the building and the Harbour Pilots occupied the single-storied concrete building on the roof.

The tower was acquired by Portsmouth City Council in 1960, and an extensive restoration project was undertaken between 1979 and 1986. The tower was opened to the public in 1987.

Restoration
Portsmouth City Council carried out an extensive restoration of the tower between 1979 and 1986, during which a detailed archaeological survey was undertaken. Excavations in the basement area, backfilled during the 18th century, revealed that it had originally been flagged, many of the stones having been reused on the western side of the ground floor. An intact stairway with doorways at basement and first floor levels and a blocked window were also revealed. The tower walls were found to have been built directly onto the shingle bank of Portsmouth Point. Examination of the interior walls of the tower revealed surviving 16th century features including stairways, windows and fireplaces, together with many later modifications ranging in date from the 17th to 20th century. The survey revealed that the interior had been lined with red-brick since Tudor times, the doors, windows and fireplaces of this period having dressed-stone jambs and red-brick arches. A white lime-wash had been applied to the main walls during the 16th century.

The survey concluded that many important features within the Square Tower had been lost or disfigured when the building was converted to a meat store in the late-18th century. The detail on the exterior walls had been covered up when the tower was refaced with Portland stone in 1827, and later-19th and 20th century modifications had also left their mark. However, many interesting and important features, some of 16th century date, were found to remain and were well preserved.

During the restoration a number of more modern features were removed from the roof, including rusty iron rails and a concrete building. The roof was reclad with flagstones and three gun positions were reconstructed on the south-west side as near-authentic to the late-19th century originals as possible. The parapet was repaired, and renovation to the external walls was carried out with drainpipes and electrical cables tied up or removed.

Inside the tower a blocked doorway in the north-west wall was reopened to allow additional access to the building at ground floor level. Access from Ten-Gun Battery to the first floor and the stairway to the roof was also renovated. The 20th century concrete first floor structure and red-brick partition walls were demolished.

The bust of Charles I which resided in a niche in the exterior wall of the tower was cleaned and re-gilded. The restoration of the bust revealed it had been modelled in lead with external gilding. The interior was hollow and had been filled with lime-mortar and fragments of red-brick and tile, with a bovine cannon-bone placed centrally and vertically within the fill. The bust was attached to the wall of the tower by an iron spike. Following restoration the bust was replaced by a fibreglass replica. The original is held by Portsmouth Museum Service.

[1]


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The Square Tower fortification and Governor's residence. C1494, extensively altered to form a powder magazine c1580 and then the Admiralty Victualling store c1780, reinstated as part of the fortifications mid C19; restored 1978-1985. Stone and brick. Flat stone paved roof with 3 restored mid C19 gun races facing south-west. EXTERIOR: south-west part 1 storey and north-east part 2 storeys. 2 bays. Main entrance facing south-east within enclosed yard has on right a 2-leaf late C20 copy of the original C18 doors with lower panels and vertical iron bars to upper panels set under a segmental stone arch with rusticated voussoirs and jambs. On first floor is a mid C18 2-leaf 20-pane casement. To left at saluting platform level is a late C20 boarded door leading to roof area and to late C20 visitors' viewing balcony. North-west façade has on left a late C20 boarded door set within C15 opening. On right is an C18 2-leaf casement set within C15 opening and further right is a late C20 replica of the original C18 panelled door with vertical iron bars to top panel. First floor has on left a mid C19 2-leaf 4-pane casement and on far right a late C20 glazed infill. On north-east side facing Broad Street is a niche edged with a wreath. This contains a late C20 copy of a gilded lead bust of Charles I by Hubrecht le Sueur (original restored and now deposited in the City Museum). Below are the Royal Arms on a small bracket and the inscription reads "After his travels through all France into Spain and having passed very many dangers both by sea and land he arrived here the 5th day of October 1623". INTERIOR: the late C20 restoration has uncovered Tudor features including two fireplaces and C18 features which include a stone stairway on north-east side running from ground to former basement. (Berridge DW: Restoration of Square Tower, Old Portsmouth, 1985: Portsmouth: 1985-; Balfour A: Portsmouth: London: 1970-: 15; Corney A: Fortifications in Old Portsmouth: Portsmouth: 1965-: 15, 16, 17; Lloyd DW: Buildings of Portsmouth and its Environs: Portsmouth: 1974-: 55, 57, 58 AND 59). [2]

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Built in 1494 as a fortified residence for the military governor, continuing in this use until c.1580. Adapted as a gun-powder magazine c.1580. Converted to a meat store for the Admiralty in 1779. Semaphore station from 1823-1848. Refaced in stone in 1827. [3]


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Archaeological monitoring carried out during repair works to the ground floor in 2024 revealed that the ground floor floorboards and joists in the north-eastern part of the tower were originally installed as part of a programme of alterations carried out in one phase during the 18th century which saw the insertion of the brick spine wall and new floors within the building, brick vaulting at ceiling level and the infilling of the basement. The joists in this section of the floor had previously been thought to have dated to the 19th century with re-used 18th century floorboards being placed on top.

Dendrochronology analysis carried out as part of the monitoring and recording works dated the first floor timbers above this section of the ground floor to produce a precise felling date of the winter of 1734/5, suggesting that the alterations were carried out in 1735 or shortly after, not 1779 as had been previously thought. [4]

<1> Fox, Russell, The Square Tower, Old Portsmouth, Hampshire (Unpublished document). SPM389.

<2> Historic England, The National Heritage List for England (Index). SPM35.

<3> Portsmouth City Council, n/a, Portsmouth City SMR Cards (Index). SPM1.

<4> Anely, George, 2024, Report on a Programme of Archaeological Works at the Square Tower, Broad Street, Old Portsmouth, PO1 2ND (Unpublished document). SPM661.