War Office War Office (Ministry Of Defence)

Government offices, built in 1898 and completed in 1907 by William Young with his son Clyde Young and Sir John Taylor. The building is constructed of Portland stone with slate and leaded roofs. It is the second of a pair of large government office blocks begun in 1898, drawing on similar English Baroque architectural influences to a design by Brydon, although the composition is somewhat cramped. The building is distinguished by the bowed corner pavilions topped with Baroque cupolas which conceal the irregular shape of the deep island site; these cupolas are an important element of the Whitehall roofscape, particularly when viewed from St. James's Park. The building is five storeys high, comprising a ground floor and mezzanine, a first floor on a basement which acts as a podium, two main storeys, and an attic storey above. The corner pavilions are surmounted by two-tier cupolas.

The central nine-bay block is flanked by one-bay aediculed pavilions and features three-window bowed corner pavilions. The wall plane is channeled, with ashlar orders and dressings in bold relief. The main entrance has a tetrastyle portico with rusticated Doric columns, a deep entablature, and a parapet displaying a coat of arms. The windows are recessed glazing bar sashes; those on the two main storeys have Gibbs surrounds, set within a giant Ionic colonnade to the main block and similar detailing to the bowed corners. Segmented, pedimented, and Ionic pilastered aedicule-pavilions frame large rusticated Venetian windows. A deep entablature sits above the third floor, followed by a blind attic over the main block, which steps up behind the aedicule-pavilions, incorporating large figure sculptures on segmental pediments. The bowed corners have architraved attic windows and the stone domed cupolas feature pairs of columns diagonally set to their main stages. Similar details are present on the other elevations, with the Horse Guards Avenue front featuring a central triple archway leading to a main courtyard.

The Whitehall entrance leads through a low hall to an ambitious main staircase of a grand club design, starting in a single flight and dividing to rise along three walls of a glazed dome compartment. Offices include 13 reset 18th-century marble chimney pieces acquired in 1904 from former War Office premises in Pall Mall.