Ploërmel takes its name from Armel, a 6th century English monk but little remains of its illustrious past. The St Armel church has some fine stained glass and granite tombstones in the transept.
The astronomical clock, classed as a national monument, was built in the 19th century and has 10 panels depicting the solar system. The Maison de Marmousets in Rue Beaumanoir is the most famous landmark in the town and has some marvellous wood sculptures on its facade.