The Belogradchik Rocks are a belt of red sandstone towers thirty kilometres long in the northwest corner of Bulgaria, near the Serbian border, rising up to 200 metres above the forest in shapes that centuries of villagers have named, with a fortress built into the middle of them where the cliffs do most of the work. The towers are what erosion left behind: blocks of sandstone cemented hard with iron stayed standing while the softer rock around them washed away, and the iron is why they are red all the way through, laid down under a hot, dry climate 200 million years ago. Their shapes are the valley's storybook. Base trails pick out the figures locals christened over the years, Adam and Eve, the Bear, the Dervish, the Horseman, and the Schoolgirl, one of the tallest towers, a convent novice who in the story was chased through the rocks by a monk until the whole scene, girl, monk and bear, turned to stone.
The fortress is Kaleto. Its gates open onto a courtyard hemmed by sheer red cliffs, and Roman foundations, medieval Bulgarian walls and nineteenth-century Ottoman ramparts stack against the living rock, since every builder used the towers as walls and only closed the gaps; stairs climb through three courts to the top of the rocks, where the whole belt of towers stands in rows to the horizon with the town of Belogradchik below. After dark the sky takes over. A short walk from the fortress stands an observatory of the Bulgarian Academy of Sciences, under some of the darkest skies in the country, and its staff aim research telescopes at the planets and the Milky Way for visitors. In autumn the beech and oak forests at the foot of the towers burn orange and gold beneath the red rock. Belogradchik is a town with a wall of stone giants, and people have been naming them for as long as they have lived under them.