In 1051, a group of monks founded a cave monastery in Kyiv. And while they eventually built some buildings aboveground (including a bell tower and a cathedral), they really extensively took over the caves, moving further and further into rock, eventually carving out a series of tunnels and chapels and storerooms.

If that’s all they did it would be interesting enough. But the site is filled with what is delightfully known as “imperishable relics.” As the monks died, they were interred in that same system of caves, and miraculously — whether this truly counts as miraculous depends a lot on your faith, granted — the bodies were preserved, mummified by the particular conditions underground.

Over the centuries they’ve been wrapped in elaborately decorated shrouds, and placed in glass coffins, set to the side of the narrow passages. There are over 100 bodies there, scattered throughout the complex. The mood is somber; it’s an active pilgrimage site, so you’ll often be shuffling along amidst petitioners silently paying their respects to each and every one of the saints. There’s no electric lights, either — you can buy a candle to carry with you, cupped in your hand to catch the wax.

For me, it’s not that it’s so creepy and morbid (although it certainly is that) but it genuinely feels holy, there. I’ve visited hundreds of churches, seen gothic monstrances and neoclassical temples, and many of them are breathtaking.

Kyiv Pechersk Lavra isn’t breathtaking. But it’s something else, something peaceful and holy and foreboding. Maybe it was the incense, or the heat from all those candles lighting the way. But I found it deeply moving, in a way dark and mysterious and utterly unique.