A small, mysterious site in the Czech Republic’s Šumava mountains could have been a nature retreat for religious hermits 2200 years ago.

At 802 metres, it’s the country’s highest Late Iron Age site, hidden in a forest near a river in Bohemia. Archaeologists found it in 2011, the site betrayed by an uprooted tree that exposed pottery fragments from the La Tène culture. But its purpose has baffled researchers.

Now, a recent excavation hints at …