Early in the 2nd century a large sumptuous building was rebuilt on the south bank of the Thames, facing out across the river. Excavations in 1983-84 uncovered a well-appointed suite of rooms, revealing parts of seven rooms, five with underfloor heating.
There was a bath-house with a well-preserved hot room (caldarium) and with a heated plunge pool attached. The bath-house is the second largest known from Roman London. The high status of the complex is indicated by a fine wall-painting from the bath-house on a par with those from Pompeii. It depicts a cupid standing within an architectural scheme of columns and garlands.
The three-dimensional effect is rarely found from Roman Britain. The pigments used in the painting included the expensive red pigment, cinnabar, and plaster fragments from the curved vaulted ceiling (indicated by the curved edge at the top of the wall-plaster) had gold leaf set into the surface which would have shimmered in torch light.
A military association with the building at Winchester Palace is indicated by a re-used stamped tile connected with the fleet and, more importantly, by a fragmentary early 3rd-century marble inscription. This listed members of a vexillation, drawn from several cohorts of legionary soldiers from one of the two legions based in Britannia Superior at the time (the 2nd at Caerleon or the 20th from Chester). The number of centurions included on the building inscription indicates a large vexillation.
The possible presence as a building contingent suggests that the complex housed elements of the provincial administration and the use of troops for building work indicates a military or government construction.
The bath-house and a number of the heated rooms were demolished in the late 3rd to early 4th century. The building complex continued in use until the late 4th century but in a reduced state. The contraction in size may be connected with the end of the rule by Carausius and Allectus in AD296 when Roman authority was reasserted.
This complex may have housed officials working for the governor and matched a similar official building sited opposite on the northern bank and which in the past has been called the ‘Governor’s Palace’ (see Governor's headquarters). Both buildings are thought to have been used for official use, consisting of suites of offices and both equally could have provided suitable accommodation for the governor when based in London.