The Mysterious Aquarium Grotto in Citadel Park in Ghent was converted in 1877 to a design by rocaille artist F. Dumilieu. By pouring cement over the remains of a former munitions depot, rocks, stalactites and stalagmites were recreated. Brick niches in the rock face are a reminder of the period when visitors to the 1913 World’s Fair could see exotic fish here.

When a parks department worker unlocks and opens the door, a man slithers out through the crack, shielding his eyes from the bright light. In one of the niches lies a spoon, a blanket, a half-empty bottle of water and a plastic bag containing four biscuits, a pen, a blister pack of paracetamol, another spoon and a family photograph.