Château de Ranton, castle in Vienne, France

Château de Ranton is an octagonal fortress in the Vienne, west of Loudun, ringed by a dry moat cut 3–4 metres into the limestone. Its rampart walls of squared tuffeau blocks rise 8–10 metres above the moat, with semicircular towers at the eight corners; machicolations survive only on the tower right of the main gate. The gate is vaulted in the Plantagenet style, and the courtyard buildings date from the 14th and 17th centuries.

Guillaume de Gourmont constructed this fortress between 1340 and 1345 as part of the regional defense strategy against English forces during the Hundred Years War. Renaissance-era modifications in the 16th century transformed its medieval appearance with new architectural elements.

The castle's courtyard buildings on the north-west side were rebuilt in the 16th century in the Renaissance style for a succession of Protestant families. The vaulted store rooms and granary on the south-west side remain from the 14th-century construction, so the two building campaigns stand side by side.

The castle is accessible by car via the D759 road that runs between Loudun and Thouars in the Nouvelle-Aquitaine region. Visitors traveling from Paris should plan for approximately three and a half hours of driving time.

The dry moat was cut 3–4 metres into the limestone, and the blocks removed were used to build the rampart walls. The same excavation opened a limestone face into which homes and farm buildings were dug, forming an underground village that sheltered people from pillaging bands between 1356 and 1372; some rooms were still lived in during the 1920s.