Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

A terrific purveyor of natural history objects and curios.

This Tang Dynasty behemoth is the biggest Buddha in the world.

Medicinal spa created from the mineral-rich runoff of a geothermal power plant

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Volcanically heated hot springs.

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

Museum dedicated to the terror regimes of Hungary.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

Macabre astrological automaton clock dating to the late 1400s.

A saintly relic hidden in a Prague church basement.

Cold war icon and onetime "hole" in the iron curtain.

An old department store turned Nazi prison turned artist commune.

The most visited, and possibly most controversial, museum in Germany.

Op-art architecture designed for happiness.

Pilgrimage site for star-crossed lovers.

Da Vinci's equestrian statue, 500 years in the making.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

This 17th-century street hidden beneath Edinburgh was once a breeding ground for the black death.

The most loyal of little dogs, or a Victorian era publicity stunt?

The world's largest model of our planetary system.

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