The forest boulders at the Gorges d'Apremont

The forest of Fontainebleau covers twenty-five thousand hectares, and the strange part is the rock: sandstone that broke into rounded blocks and lies scattered across the heath in fields, some the size of a car. The Gorges d'Apremont, above Barbizon and about ten minutes' drive from the château, are the most accessible of these areas and the best for photography.

What you get is unlike anything else within reach of Paris: pale grey rock, open sandy ground, heather and bracken, twisted oak and pine, and long views over the tops of the trees from the higher blocks. It has scale without mountains. The Barbizon painters worked here in the 1830s for the same reason, and today the boulders are a world-famous bouldering site — expect climbers on the rock at weekends.

Late afternoon is when it comes alive: the sandstone goes warm orange in low sun, the heather picks up colour, and long shadows separate the blocks from the ground. Autumn is the strongest season, when the oak and beech turn and the heath goes russet.

It is open forest, free and unfenced, but it is also uneven, sandy and unsigned in places: park at a marked car park, stay on the waymarked paths where you can, take water, and remember there is no shelter and no lighting once the sun goes. Shoes matter more here than anywhere else in this location.