Royal Arsenal, Royal Laboratory West Pavilion

The Royal Arsenal's Royal Laboratory West Pavilion is a disused gunpowder works built between 1694 and 1696, with extensions and alterations made in 1802. It is constructed of Flemish bond brick with stone dressings and features a slate hipped roof. The building has a single-depth plan and stands two storeys high, with a five-window range. The symmetrical front includes a pedimented entrance bay that is set forward, showcasing rusticated voussoirs, a plinth, and a plat band. The doorway is framed by an elaborate surround with an eared architrave and a console cornice, beneath a first-floor architrave adorned with foliate brackets and another eared architrave featuring a lion key. The pediment is embellished with a cartouche displaying the arms of William III. The windows have rubbed brick flat arches with keys, indicating some alterations or blocked sashes.

The interior has not been inspected but is noted to lack internal divisions or flooring, featuring a 19th-century iron roof.

Historically, this pavilion is the oldest part of the Arsenal and may be one of the oldest ordnance buildings in the country. It is one of a pair of pavilions, with the other located to the east, which are the only remaining sections of a larger structure that housed the Royal Laboratory for fireworks and gunpowder after relocating from Greenwich in 1695. Originally, there were cross windows and lower buildings on either side, with the yard enclosed to the north and south by gate piers that once supported lion and unicorn finials now found in the Board Room. The courtyard between the two pavilions was covered in 1854 and became home to the largest milling machinery space in the world until it was demolished in the mid-1950s.