Heritage Open Day: St. John's Church was built in the early 12th Century by the Bishops of Salisbury. It was initially the Church for the Castle, its governor and garrison - the Castle Church. It is now a grade 1 listed magnificent building. The church of St. John the Baptist Church, Devizes is built of ashlar and has a chancel with north and south chapels, a crossing tower, transepts, an aisled nave, and north and south porches. The later-12th-century cruciform church was of considerable size and quality. The chancel was covered by a quadripartite vault of two bays and the walls were decorated internally by intersecting arcading. The oblong tower, more than 65 ft. high, was richly ornamented both inside and out.