Réserve naturelle régionale de la forteresse de Mimoyecques, Regional nature reserve at Landrethun-le-Nord, France.

The réserve naturelle régionale de la forteresse de Mimoyecques covers 1.57 hectares around the Mimoyecques fortress in Landrethun-le-Nord, Pas-de-Calais. It was classified in 2012 to protect the galleries used as bat roosts and the rock face at their entrance, where a gravel path leads to a dark arched tunnel mouth in pale grey and tan rock.

During World War II, the German military built this underground complex as part of its defensive plans. The project was later abandoned, and the installation survived as a historical remnant from that era.

The reserve takes its name from the Mimoyecques fortress, a Second World War bunker built to house the V3 cannon. The 1.57-hectare site, classified in 2012, is managed by the Conservatoire d'espaces naturels du Nord et du Pas-de-Calais. Visitors may enter the fortress, but the bat galleries themselves are closed to the public to avoid disturbance.

The fortress itself receives the public, but the bat galleries are closed to visitors to avoid disturbing the colony. The reserve covers 1.57 hectares around the site, managed by the Conservatoire d'espaces naturels du Nord et du Pas-de-Calais. The gravel path leads to the arched tunnel mouth in the rock face.

The reserve covers 1.57 hectares around the Mimoyecques fortress, protecting the rock face at the tunnel entrance and the galleries where bats shelter. Three species are recorded there: the greater horseshoe bat, the Geoffroy's bat and the pond bat. The galleries are closed to visitors to avoid disturbing them.