The Garrison church at Castille Place was a Protestant church built around 1855 in a restrained classical architectural style having a plain front façade with corner pilasters. A small, two-column portico covers the main doorway. A triangular gable, punctured by a circular window, crowns the front elevation. A small bell-cot is located centrally above the gable. The sides are given rhythm through the alternation of pilasters and unadorned windows. The structure is covered by a double-pitched roof.

The Church was built above two vaults within the Valletta fortifications, one of which served as a crypt when the chapel was in use. Throughout its history the Garrison church served for various purposes other than the original including as a military social club and as the Malta Central Mail Room. It was converted into the Malta Stock Exchange in 1999, as it remains to date.

This building is the only one surviving out of four similar churches built by the British. It is also one of the few buildings in Valletta having a double-pitched roof in contrast to the many flat roofs.

Mepa scheduled the Garrison church as a Grade 1 national monument as per Government Notice No. 276/08 in the Government Gazette dated March 28.