Rare Octagonal Bath House
The summer excavation of the Kent Archaeological Field School was on a possible Roman building, located by fieldwork as part of the Swale Archaeological Survey in 2000. 67 students from most of the major universities in Britain gathered for a week's training and excavation, at the end of which we exposed a large part of a unique and magnificent late Roman octagonal structure with a huge octagonal central plunge bath. This bath had been re-built in the early 5th century as a smaller circular central plunge bath with a fountain. The blue-coloured fresco floor still survived, as did the Roman lead water pipe leading from the massive earlier Roman brick conduit. Our evaluation trench also revealed the concrete base of an enormous Roman corn mill, and a huge ‘holloway’ road leading down from other Roman buildings - again revealed by evaluation - to a possible harbour. Earlier Iron-Age ditches and later Anglo-Saxon buildings all added to the rich repertoire of the site.
The octagonal bath house is unusual, unique in Kent and even south-east Britain. The structure is about 10 metres across and has arcading surrounding the huge central octagonal pool, itself over 5 metres wide. The pool still had in situ a massive brick conduit built to supply fresh cold water. The walls of the building were originally covered with highly decorated painted plaster and the floors with tesserae in black, yellow, red and blue, which were smaller than usual. Smaller marble mosaic cubes were also retrieved which suggest that some of the floors had mosaics.
Octagonal buildings of this type are to be found in the West Country at Lufton and Holcombe; others are further afield in Ravenna, and of course, Rome. The function of these elaborate and exotic buildings has often been discussed, but some experts keep returning to the idea that the astonishing octagonal frigidarium in the centre could have been used for Christian baptism or even Jewish sacred bathing. This scenario has been reinforced at our site by the finding of a Roman lead seal probably depicting the Jewish minora.
Some rooms had underfloor heating as well as alcoves which contained hot plunge baths. It is logical to assume that above the central pool and its fountain was a vaulted ceiling, carried on arcading or columns. Some elements of a stucco ceiling - again unique - had survived, and possibly a large dome set on pendentives that would have echoed and reflected the sound of cascading water. Ceilings such as these would have been possible with the columns or arcading bearing the vertical pressure, and the surrounding ground floor rooms providing a buttressing effect to counteract outward thrust. This is very sophisticated Roman engineering and belongs more to the late Roman and Byzantine Mediterranean world, opening discussion on why, and also how late, such Roman influences were prevalent in Britain.
Dr. Paul Wilkinson
ABOVE: Plan of the excavated area.
BELOW: A member of the KAFS standing in part of the brick conduit which fed cold water to the 5 metre octagonal plunge pool. Built in the 4th century and rebuilt in the early 5th by a much smaller circular pool, it still has its blue fresco paint and lead pipe to the fountain.