There is an high number of castles and manors in the area. Nearly all are private properties. Some can be visited.
Here a small extract:
Château du Hac, le Quiou (30 km - the photo)
Tel. 0033.2.96.83.43.06
Fax 0033.2.96.83.49.54
web wikipedia
Château la Bourbonsais, Pleugueneuc (15 km)
Tel. 0033.2.99.69.40.07
Fax 0033.2.99.69.46.04
web
Château de Combourg (25 km)
Tel. 0033.2.99.73.22.95
web
Château de Montmuran, Les Iffs (35 km)
Tel. 0033.2.99.45.88.88
web
Museum Manoir Jacques Cartier Saint Malo (12 km)
Tel. 0033.2.99.40.97.73
Fax 0033.2.99.40.82.63
web
Château du Hac
Malouinière du Puits Sauvage Saint Malo (12 km)
Tel. 0033.2.99.82.22.48
Malouinière du Bos Saint Malo (7 km)
Tel. 0033.2.99.81.40.11
Château/Parc de Caradeuc Becherel (35 km)
Tel. 0033.2.99.66.77.76
Château de Landal Broualain (20 km)
Tel. 0033.2.99.80.10.15
Château de Fougeres (80 km)
Tel. 0033.2.99.99.79.59
web
Château de Lanrigan (35 km)
Tel. 0033.2.99.73.04.55
Malouinière du Montmarin Pleurtuit (18 km)
Tel. 0033.2.99.88.58.79
web
Château de Vitré (80 km)
Tel. 0033.2.99.75.04.54
web