Village Underground Lisboa, an international platform for creativity, art, and culture, built with two buses and 14 shipping containers converted into creative spaces, Lisbon, Portugal, Europe

Village Underground Lisboa, an international platform for creativity, art, and culture, built with two buses and 14 shipping containers converted into creative spaces, Lisbon, Portugal, Europe

Orthodox priest taking collection at Piata Romana underground station, General Gheorghe Magheru Boulevard, Bucharest, Romania

The Catacombs in the Church of St. Francis, Porto, Norte, Portugal, Europe

View of interior and train at Abholer-Parkplatz Spandau Bahnhof, Spandau, Berlin, Germany

The Agape Table, St. Pauls catacombs, Rabat, Malta

Cave hotel in Sassi di Matera, Basilicata, Italy, Europe

Crypt, Lecce Cathedral (Cathedral of Maria Santissima Assunta and Sant'Oronzo), Lecce, Salento, Apulia, Italy

Crypt, Lecce Cathedral, Cathedral of Maria Santissima Assunta and Sant'Oronzo, Lecce, Salento, Apulia, Italy

A caver in Valley Entrance, Kingsdale, Yorkshire Dales, Yorkshire, England, United Kingdom, Europe

A caver in a tight squeeze in the Yorkshire Dales, England, United Kingdom, Europe

Hikers standing at entrance of cave

Camp life in what was termed 'The Geode Cafe' due to the crystal coated walls of this particular sandy space in Moon Cave.