The church of Saint-Martin in Floyon, one of the few fortified churches in the Avesnois, was destroyed during the War of the Burgundian Succession in the 15th century and rebuilt after the peace treaty of Senlis.

The present church dates from 1573, this date appears together with the village’s coat of arms on a blue stone above the Renaissance portal. The same stone is also found in the composition of the foundation walls of Saint-Martin, which is a tradition in the Avesnois.

Saint-Martin was again a victim of flames in 1637 and suffered further damage in the 17th century, which suggests that further restoration work was carried out. The choir in particular was rebuilt in 1825.

The only feature of fortification is the high tower on the right flank of the brick bell tower, which gives access to the floors of the escape rooms.

The porch is in Renaissance style. The church contains relics of Saint Ursmar, a bishop who evangelised Flanders and Hainaut in the 7th century, and was born in Floyon in 644.