St John the Baptist's church dominates Cirencester's market place so thoroughly that locals call it the Cathedral of the Cotswolds, despite never having had a bishop to its name. It is the largest parish church in Gloucestershire, begun in the mid-12th century.

Much of its grandeur came from King Henry IV, who funded an expansion in the 1400s as thanks for the town's loyalty: its garrison had captured rebel earls plotting to restore the deposed Richard II, though a botched rescue ended with a mob beheading the captives instead. Henry's money also raised the tower, whose builders discovered too late that its foundations sat atop an old Roman drainage ditch. The tower began to lean, its spire was scrapped, and flying buttresses were added to keep it upright.

Owen Bowles's VoiceMap tour uses the church as centrepiece, tracing Cirencester's rise from Roman Corinium through its wool riches and beheaded earls.