Fort van Haasdonk, Military fortification in Haasdonk, Belgium

Fort van Haasdonk is a military fortification with a trapezoidal design surrounded by a wide moat in Beveren near Antwerp. The structure sits within a protected area and displays the typical features of an early 20th century defensive installation.

The fort was built between 1908 and 1913 as part of Belgium's broader defense strategy to protect the region. Despite its purpose, it saw no combat and remained inactive through both World Wars before being abandoned.

The fort is named after Haasdonk, the village in Beveren where it lies. It is not open to the public: since 2005 it has been managed by NatuurpuntWAL as a bat reserve, and counts in 2006 recorded about 268 hibernating bats of five species, mainly the pond bat and the barbastelle. It is also the only place in Belgium where German feltwort grows.

The fort is not accessible to the public; it is managed by NatuurpuntWAL as a bat reserve, so visits must stay outside the perimeter. The whole site is still zoned as military area on the regional plan. The moat is 50 m wide and the fort covers about 22 hectares, so the outer circuit is long; the entrance road and the supervisors' houses are part of the protected monument.

The fort is the only place in Belgium where German feltwort grows, and winter counts in 2006 recorded about 268 bats of five species, mainly Daubenton's and barbastelle bats. It is not open to the public.