The base of 18th-century Cathédrale St-Jean's bell tower houses an incredible astronomical clock, powered by 11 weights, that has run the church's bells since its installation in 1860. The ornate gadget has 30,000 moving parts and 57 clock faces and, among other things, tells the time in 16 places around the world and indicates the tides in eight different French ports.
Shutterstock / Philip Bird LRPS CPAGB