The entrance hall is located in the centre of the west range at Syon. Its double cube size had been dictated by the pre-existing fabric, but Adam was commissioned to redecorate. He began work here in 1761, installing a Roman-style interior, with bas reliefs by Joseph Wilton. The decorative scheme was executed in accordance with Adam volumes 27/35 and 39/3, but with alterations. There is no chimneypiece within the alcove at one end of the room (as seen in Adam volume 27/35), but instead Adam designed a pedestal (Adam volume 49/47) to support a cast of the Apollo Belvedere. At the other end of the room the executed wall is an alternative to both drawings, with a central door within a large and deep relieving arch - or arched recess - accessed by curving staircases hidden by a statue of the Dying Gaul.

There is a sideboard table in the room which is not shown in these laid out wall elevations, and nor is there a drawing for its design. It is, however, undoubtedly by Adam, and too large to have been intended for any other room in the house. Its location within the hall - currently in front of a statue of the Dying Gaul - is probably not original, however, as it is ornamented all the way around the table rail, suggesting that it was intended to stand in a location where it could be seen from every angle.

There are four engravings of the hall at Syon in The works in Architecture of Robert and James Adam. Volume I contains a section of both ends of the room, and an engraving containing various ornamental details, and volume II contains a section of the room, and further details.