This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

The stunning interior of this Gothic church is covered in ornate gold details.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Houses are tucked between, on, and underneath giant boulders.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A marvel of technology a century ago, this disused power station now offers a lovely glimpse into the industrial design of the past.

The abandoned military base looks like a post-apocalyptic wasteland.

A collection of intricate sculptures so small they have to be seen through a microscope.

A random tree outside a Budapest hotel has become a DIY shrine to the late singer.

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

Sitting beneath an unremarkable residential building is a museum devoted to classic Pinball.

Once the home of a hermetic monk, this cave now houses a small church.

This off-beat, quirky communism-themed bar isn't afraid to poke fun at its history.

This ancient monastery complex was transformed from an island to a peninsula when the lake was partially drained.

A scenic canyon with thick forests and historic ruins.

The temple that withstood the Nazis.

The social hall of this former factory is a Communist-era time capsule.

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

Bronzes and busts that once stood in the city's main squares are now relegated to a small hidden courtyard.

A galaxy of glowworms—larvae of a gnat—hides deep in the belly of these caves.

Hundreds of toothbrushes hang from a wire fence along a quiet New Zealand road.

Luxury hotel turned into a refugee camp, then turned back into a luxury hotel.

These Stalin-era industrial 'death traps' hang lifeless above the city