Sint-Medarduskerk, Catholic church in Wervik, Belgium

Sint-Medarduskerk is a Gothic church in Wervik, 81 metres long, 37 metres wide and 86 metres tall at the tower. The choir, radiating chapels and transept are built of grey-brown Arras sandstone, while the nave and tower use light Balegem stone. The tower spire dates from 1901.

A first parish church dedicated to Saint Medard was begun around 1214, when Wervik's Romanesque Sint-Maartenskerk had become too small; only its early Gothic octagonal crypt survives beneath the present choir ambulatory. Breton troops destroyed that building in 1382, and the current church was started at once on the same site, twice as large. It was nearly finished in 1414 and completed with the tower in 1433.

The church is named after Saint Medard of Noyon, a 5th–6th-century bishop of Vermandois and patron saint of brewers, prisoners, and vineyards. In the 16th century the crypt became known as the Baronkelder after a baron-bailiff was buried there; children dared each other to put a hand through the cellar window and call out to the baron.

The church reopened to visitors following major restoration work completed in 2012, allowing access to view its medieval interior features. Check opening times in advance, as the building's availability depends on services and local events.

The claim that Archdukes Albert and Isabella called it Flanders' finest church in 1608 is a legend: the building then lay in ruins and only got its roof back in 1620. The crypt, called Baronkelder since a baron-bailiff was buried there in the 16th century, inspired ghost stories of singing and rattling chains.