Roche Abbey is a ruined Cistercian monastery set in a quiet limestone valley near Maltby, east of Rotherham and within day-trip reach of Doncaster. The surviving early Gothic transepts still rise with surprising height, while the excavated ground plan lets you read the shape of the medieval abbey.
The setting matters almost as much as the masonry. In the 18th century the ruins were folded into a designed landscape associated with Capability Brown, so the place has both monastic austerity and a later taste for romantic decay. Bring a picnic if the weather is kind; it is the sort of ruin that rewards lingering.