These "50 Fortresses" have been unearthed in the ancient oasis of Khwarezm.

Final palace complex of the last of 29 Kokand rulers.

This "tower of death" has acted as an observatory, a religious hub, and an executioner's lair.

Ancient barriers wrap around what was once an important stop along the Silk Road.

Light still pours into the ruins of this ancient Islamic observatory.

Once a bustling fishing port, this semi-ghost town is now more than 90 miles away from the shore.

The Avenue of Mausolea is a series of grand palatial tombs.

A cathedral resurrected from the ashes of one of Europe's greatest urban fires.

A replica of the home of a famous fictional troll family.

Collection of nearly 500 concrete figures sculpted by the late Veijo Rönkkönen.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

Architecturally stunning library serves as the hub of Finnish scholarly life and culture.

A subterranean house of worship carved right out of the bedrock.

Every summer local children form "pysja patrols" to save young birds that have wandered from their nests.

This mountain fissure hides a secret path to a secluded mossy grotto within the rock itself.

This black church sits alone among a field of lava rock.

This scenic Icelandic lava flow is named for a pair of Berserkers who were murdered, according to a famous Saga.

At this museum in Iceland, visitors can sample fermented Greenland shark.

A beautiful Arctic museum and nature center preserves the culture of the Sámi people.

At the very tippity-top of Europe is a cliff from which you can view the midnight sun.

The world's most charming instant portrait studio also happens to be its smallest.

The world's northernmost aquarium looks like it has fallen over.

This functioning parish church is also the site of many concert performances due to its wonderful acoustics.

Roughly 17 million letters to Santa have found their way to this Arctic Circle post office.