Where the lovelorn find a home for their sentimental keepsakes.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Climb inside an iron crystal magnified 165 billion times its normal size.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

Moscow's other, lesser known kremlin is a fairytale-like cultural complex modeled after Old Russia.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

Once part of an ancient international harbor, it's now an all-you-can-eat shrimp buffet for flamingos and other water birds.

Launch site for nuclear war against Western Europe.

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

A whimsical bridge adorned with decorative dragons.

This abandoned Slovenian military barracks has become a punky-political art squat.

The oldest housing complex in Riga is a mini timeline of architectural trends.

3,000 market stands in five former Zeppelin hangars.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A war-torn Olympic relic is being overtaken by graffiti and nature.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

Bridge that died in war and was resurected.

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

Established in 1638 to battle the Black Death, this botanical garden is a treasure trove of rare flora.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.