Complex aquaponics systems allow fish and plants to grow in harmony.

Once a speakeasy operated by Al Capone, this Milwaukee cigar bar is now a haven for ghost hunters.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

This naturally-sourced hot spring is now home to a clothing-optional resort.

Roman ruins top white travertine terraces formed by ancient hot springs.

The ancient latrines of the Greeks, in all their public glory.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

A sacred mountaintop temple offers a fine cup of tea to visitors who can survive the journey.

The deadliest diving spot in the world is also a stunning geological marvel.

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.