Keystone

The building projects over the pavement with an arched colonnade for pedestrians. On the keystone of each arch, at the ends and along the length, there is a head in relief. The west side of the building has been joined to the building on the other side of Throgmorton Avenue with a bridge (see the building next door for a picture) and to the south of this bridge the building carries another keystone head. The bridge is a later addition and it seems likely that originally there were still more keystone heads where the bridge now is. Most of the keystones are helpfully inscribed on their underneath with a name identifying their head, but three are anonymous. Reading the photograph from left to right the heads are:
Soane
William of Wykeham
anonymous
anonymous but identified as Inigo Jones
anonymous satyr
Wren
Vanbrugh
Barry

Wren and Vanbrugh could be sharing the same wig. We've spotted that all the identified personages were architects so that narrows the field for the remaining unknown.

Under the bridge is the entrance to the building, around which there are three inscribed stones. Two of these are rather dull:
- a copy of the inscription of the foundation stone for the original building, laid in 1876,
- commemorating the opening of the Hall on 4 May 1960.
The third is the stone recorded here concerning the start of the rebuilding.

Above the door: SVRREXIT DOMVS, MCMLIX. Translation-guide renders this as "To get up household, 1959", but we get the idea.