This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

A small island dotted with old, historic Finnish buildings.

The church's remarkable frescoes incorporate Finnish artist Hugh Simberg's trademark themes of death and the supernatural.

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

An abstract monument to a symphonic composer.

18th century opera in its original splendor.

Sweden's "good old days" painstakingly re-created in a model village.

It houses the remains of a 17th-century version of the Titanic.

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

Across the Pacific in a raft, a museum dedicated to Thor Heyerdahl's now legendary expedition.

One of the most breathtaking railways in Europe also takes one of the steepest climbs, from fjord to mountain plateau.

The convergence of two currents makes this a surprisingly pleasant getaway in the Arctic Circle.

Home to three historic ships from the age of Vikings.

This beautiful, historic church looks like something out of a simpler past.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

A strange egg in a mucky bog of western Ireland marks the spot of an aviation milestone.

The modern birthplace of Irish freedom.

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

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

This single room has survived the centuries with almost no deterioration.

Belfast's namesake river still winds below the city center, hidden from sight.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

Northern Ireland's Brobdingnagian stepping stones.