It is a stone building in a semi-Gothic style intended to be sympathetic to the historic Guildhall, which is adjacent and to which it is connected internally.

The City of London Corporation had commissioned and collected portraits since 1670, originally to hang in the Guildhall.

This building was destroyed in The Blitz in 1941, resulting in the loss of 164 paintings, drawings, watercolours, and prints, and 20 sculptures.

[5] The centrepiece of the collection, John Singleton Copley's huge painting depicting The Defeat of the Floating Batteries at Gibraltar, was placed in a prominent position in the entrance hall of the gallery.

[7] The Guildhall complex was built on the site of London's Roman amphitheatre, and some of the remains of this are displayed in situ in a room in the basement of the art gallery.