Some 200L of water per second gushes from Fosse Dionne, a natural spring near the centre of Tonnerre that was sacred to the Celts and whose vivid blue-green tint hints at its great depth. Legend has it that a serpent lurks at the bottom. Forming a picturesque backdrop behind the great circular pool are a mid-18th-century washing house, a semicircle of ancient homes and a steep forested hillside.

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Lonely Planet's must-see attractions
Abbaye de Fontenay
24.58 MILES
Founded in 1118 and enshrined as a Unesco World Heritage site, Fontenay Abbey offers a fascinating glimpse of the austere, serene surroundings in which…
Basilique Ste-Madeleine
28.89 MILES
Founded in the AD 880s on a former Roman and Carolingian site, Vézelay's stunning hilltop basilica was rebuilt between the 11th and 13th centuries. On the…
Musée du Pays Châtillonnais Trésor de Vix
28.13 MILES
Châtillon’s main claim to fame is the Trésor de Vix (Vix Treasure), a collection of Celtic, Etruscan and Greek objects from the 6th century BC on display…
Abbaye de Pontigny
12.46 MILES
Founded in 1114, Abbaye de Pontigny rises from the lush mustard fields 15km north of Chablis. The spectacular abbatiale (abbey church) is one of the last…
Abbaye St-Germain
18.89 MILES
This ancient abbey with its dramatic flying buttresses began as a basilica above the tomb of St Germain, the 5th-century bishop who made Auxerre an…
Tour de l'Horloge
19.11 MILES
In the heart of Auxerre's partly medieval commercial precinct, the golden, spire-topped Tour de l'Horloge was built in 1483 as part of the city's…
Château d'Ancy-le-Franc
10.57 MILES
The Italian Renaissance makes a cameo appearance at this imposing château, built in the 1540s by celebrated Italian architect Serlio. The richly painted…
Cathédrale St-Étienne
18.94 MILES
This vast Gothic cathedral and its stately 68m-high bell tower dominate Auxerre's skyline. The choir, ambulatory and some of the vivid stained-glass…
Nearby Yonne attractions
1. Hôtel-Dieu
0.21 MILES
This charity hospital, founded in 1293 by Marguerite de Bourgogne (wife of Charles d’Anjou), is most famous for its vast, barrel-vaulted patients' hall…
2. Musée Chevalier d'Éon
0.32 MILES
Tonnerre's newest attraction is this house-museum, once home to the colourful Chevalier d'Éon, a gender-bending 18th-century diplomat and spy. The…
3. Château de Tanlay
5.36 MILES
Dominating the northern edge of the tranquil riverside village of Tanlay, the elegant French Renaissance-style Château de Tanlay is surrounded by a wide…
4. Synagogue
8.41 MILES
For a free tour of this lovingly restored 16th-century synagogue, just knock on the door during regular opening hours.
5. Église St-Martin
8.42 MILES
The 12th- and 13th-century Gothic Église St-Martin, first founded in the 9th century by monks fleeing the Norman attacks on Tours, is two short blocks…
6. Petit Pontigny
8.46 MILES
The 12th-century cellar of Petit Pontigny (viewable from the exterior only) was once used by Pontigny's Cistercian monks to ferment wine.
7. Château d'Ancy-le-Franc
10.57 MILES
The Italian Renaissance makes a cameo appearance at this imposing château, built in the 1540s by celebrated Italian architect Serlio. The richly painted…
8. Château de Maulnes
11.58 MILES
The only château in France built on a pentagonal plan, and buttressed by five towers, the Renaissance-era Château de Maulnes, 24km east of Tonnerre, is a…