Hmp Perth, A And B Halls, Crescent Block

At the centre of A and B Halls is a crescent shaped Tudor style observation block of 5 and 4 storeys by Thomas Brown and dating to 1839-42. It consists of an advanced two bay 5-storey central tower flanked by slightly lower curved 4-storey crenelated blocks which are in turn flanked by lower curved crenelated single bay 4-storey sections. The crescent block is constructed of squared and coursed whinstone with cream sandstone ashlar margins and quoins. There are chamfered openings and some openings have hoodmoulds. There are replacement steel-framed multi-pane windows to the rear.

A Hall (to the left of the crescent) and B Hall (to the right of the crescent) are imposing 4 storey crenelated cell blocks constructed in cream ashlar. B Hall at 24 bays is slightly longer than A Hall but they are in the main largely similar. Both have advanced taller 2-bay inner corner sections with machicolation. Both have slightly advanced later outer bays added in 1876 (3 bays to A Hall; 4 bays to B Hall) and large near-central crenelated ventilation chimneys. There are some segmental and round-headed openings particularly to the inner and outer bays, but most are regularly-spaced small rectangular openings with chamfered margins. There are replacement timber multi-pane windows.

The interior of A and B Halls, partially seen in 2014, comprise a corridor plan with four floors of regularly spaced cells opening off either side of the corridor. There are few architectural features and the design is simple and functional. The basement of A Hall (now not used for prisoner accommodation) has some surviving early narrow 2-panel timber cell doors with an observation hole and a central rectangular letter-box type opening. There are some surviving sets of vertical metal bars forming barriers (central gate not extant) which are no longer used but which appear to conform to Brown's description of the design of the cell blocks and are likely to date from Matheson's work of around 1852-9.

In front of the Crescent Block is a two storey 5-bay flat-roofed building with a crenelated parapet now known as the Tower Board Room. It was originally built by Robert Reid in 1810-12 (it formerly had a tall observation tower which is thought to have been demolished in the 1960s) and it was extensively altered by Thomas Brown in 1839-42 to form the Governors' Office and a reception centre for new inmates. It is constructed in squared and coursed whinstone with cream ashlar margins and quoins. It has a two-way forestair to provide access to the central first floor entrance.