Museum devoted to the artificial language of Esperanto.

This Austrian museum celebrates the work of famous forgers and their inimitable imitations.

Macabre museum devoted to historical Viennese murders.

The final resting place for the remains of 143 Habsburg royalty.

The beautiful baroque library of the Hapsburg empire.

The library's graceful rotunda is like a bibliophile's temple.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

Gods clash with machines in a power plant regenerated as a museum.

If you want to talk to the Pope you will have to stare down this surreal vision of Jesus rising from a nuclear hell.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

A collection of objects supposedly singed by the hands of souls in purgatory.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

An alchemist's "magic door" stands in the middle of a Roman park.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Two thirds of this Montreal neon icon has survived to flash another day.

Montreal's colorful subway station shows its support of the local LGBT+ community.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

The final resting place of many of Germany's most famous communists.

One of downtown Berlin's last reminders of its Communist past.

This conical hill was built as a testing ground for an engineer known as the Glider King.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

A fascinating insight into daily life in the Eastern Bloc.