The building is designed in neo-Palladian style, following a three-storey rectangular floor plan with a central courtyard, built of masonry with load-bearing walls.
The façade, facing west towards the Grand Palace, is marked by a central pediment supported by Doric-order columns, which is flanked by two wings with gates leading into the courtyard.
Windows line all three levels of the building's exterior, which is decorated with pilasters in superimposed order.

While the front of the building is perfectly symmetrical, its wings taper towards the rear, as necessitated by the shape of the plot, which the building entirely fills except for the front lawn.
It is surrounded by streets on all sides (Sanam Chai to the west, Lak Mueang to the north, Rachini to the east, and Kanlayana Maitri to the south).
According to the original plans, the central structure was to contain an armoury and military museum on the top floor, officer's meeting rooms on the middle, and sword-fighting practice areas below.
The wings housed sleeping quarters on the upper floor, meeting and training rooms on the middle, and armouries and provisions storage areas on the lower floor.
The north wing hosted artillery units, a military hospital, and stables, while the south wing hosted infantry and engineering units.
At the rear of the south wing was a connected clock tower (since removed), which also housed water pumps and storage tanks—the building was built with metal plumbing.
The central courtyard was used for drills and exercises.

The building has undergone several additions, including an extended portico at the front, a new section running alongside the original northern wing, and annexes at the rear (east side) of the complex, where a granary and bathing and swimming pools used to be located.
The building received the ASA Architectural Conservation Award in 1997, and was registered as an ancient monument by the Fine Arts Department in 1998.
The building is designed in neo-Palladian style, following a three-storey rectangular floor plan with a central courtyard, built of masonry with load-bearing walls. The façade, facing west towards the Grand Palace, is marked by a central pediment supported by Doric-order columns, which is flanked by two wings with gates leading into the courtyard. Windows line all three levels of the building's exterior, which is decorated with pilasters in superimposed order.
While the front of the building is perfectly symmetrical, its wings taper towards the rear, as necessitated by the shape of the plot, which the building entirely fills except for the front lawn. It is surrounded by streets on all sides (Sanam Chai to the west, Lak Mueang to the north, Rachini to the east, and Kanlayana Maitri to the south). According to the original plans, the central structure was to contain an armoury and military museum on the top floor, officer's meeting rooms on the middle, and sword-fighting practice areas below. The wings housed sleeping quarters on the upper floor, meeting and training rooms on the middle, and armouries and provisions storage areas on the lower floor. The north wing hosted artillery units, a military hospital, and stables, while the south wing hosted infantry and engineering units. At the rear of the south wing was a connected clock tower (since removed), which also housed water pumps and storage tanks—the building was built with metal plumbing. The central courtyard was used for drills and exercises.
The building has undergone several additions, including an extended portico at the front, a new section running alongside the original northern wing, and annexes at the rear (east side) of the complex, where a granary and bathing and swimming pools used to be located. The building received the ASA Architectural Conservation Award in 1997, and was registered as an ancient monument by the Fine Arts Department in 1998.
Ministry of Defence headquarters (Thailand)