An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

Living trees form the structure of an open-air palace.

Europe's second largest ossuary wasn't discovered until 2001.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

Terrifying derelict military hospital once housed a recuperating Hitler.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Mortarless walls that stretch for miles are a lovely solution for creating grazing land in the harsh terrain of the Aran Islands.

One of the most popular megalithic sites in Ireland stands as a humbler version of Stonehenge.

A sacred well steeped in Pagan roots on the West Coast of Ireland.

This singular Irish dolmen is more Frank Lloyd Wright than upright stonehenge.

The oldest inn in Kilkenny was established by the first convicted witch in Ireland.

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

A steam trawler with a whiskey-soaked history driven ashore in 1960 resides rusty but still standing on the shoreline.

After being destroyed by IRA sympathizers, the ruins of this stately Irish manor have sat vacant for decades.

Huge standing stones mark a site of megalithic mystery.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

A standing relief of a Norman knight whose posture marks him as a Crusader.

The ruins of an 800-year-old monastery boasts the tallest round tower in Ireland.

The oldest licensed distillery in Ireland.

Just another ancient, mysterious Irish stone circle.

A hugely vast Irish landscape of barren rock that stretches for miles.

While only two of the ancient buildings at this site are actually churches this was one of the earliest Irish pilgrimage sites ever.