Substantial remains of an octagonal Roman bath house, probably reused as a Christian baptistry, have been uncovered during a student training excavation near Faversham in Kent.

The central cold plunge pool was five metres (16ft) across, and stood within a structure which also had underfloor heating and hot pools, probably originally under a domed roof.

Bits of painted wall plaster, blue floors and multicoloured mosaics were found by students from Kent Archaeological Field School.

Paul Wilkinson, who led the excavation, called the find "unique and magnificent".