Tewkesbury Abbey — formally the Parish Church of St Mary the Virgin — is one of England's finest Norman churches, begun in 1087 and consecrated in 1121. The west front is dominated by a huge Norman arch, one of the largest in England, and the tower above it is the tallest Norman tower in the country. The interior has a forest of massive Norman pillars supporting the nave, and the choir and sanctuary contain an exceptional collection of medieval tombs and monuments.
The abbey survived the Dissolution of the Monasteries in 1540 only because the townspeople of Tewkesbury bought the building from Henry VIII for £453 — roughly the value of the bells and lead on the roof. Entry is free, though donations are requested. Allow at least an hour, more if you want to read the monuments in detail.