St Mary sub Castro, Dover

St Mary sub Castro is a church at Dover Castle with a cross-shaped layout, an aisleless nave, and a central tower built from stone blocks, flint, and reused Roman tiles. The interior space feels compact and solid, with walls that show the mixed materials carefully fitted together.

The building dates to the early 7th century and ranks among England's oldest religious structures from that era. King Henry III ordered major changes to the building during the 13th century to improve and adapt its function.

The church displays early Anglo-Saxon features through its double-splayed round-headed windows and crafted door openings that reflect how builders worked in this period. Visitors can see these techniques firsthand while moving through the interior spaces.

The building is reached through Dover Castle grounds and keeps regular visiting hours for guests. A Roman lighthouse structure stands nearby and can be explored as part of the same visit.

The building incorporates stone and materials taken from an ancient Roman lighthouse structure, blending two historical periods in its walls. This reuse of Roman components reflects how medieval builders adapted earlier remains to new purposes.