The most metal church of all time was built in record time because of an international, pious pissing contest.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

A marvel of Byzantine engineering under the streets of Istanbul.

Continental Europe's only museum devoted to salt and pepper shakers features more than 20,000 designs.

One of the best examples of the modernist movement in Madrid.

A statue commemorating a beloved stray dog who was adopted by the entire neighborhood where he lived.

Dedicated to a young woman who broke gender barriers at the University of Madrid.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

Known as the Casa de las Siete Chimeneas, this haunted 16th-century manor has a dark, mysterious past.

Order cookies baked by cloistered nuns in a 400-year-old monastery.

Go surfing on this urban wave, "hacked" by local surfers.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

Famed for its pie, this eatery has a hidden tunnel that allowed Catholics to secretly walk to church during the Reformation.

A neo-Gothic mansion now houses a wunderkammer of analog tech that hits on all the senses.

This grand manse has been transformed into a museum devoted to one of the founders of Fantastic Realism.

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

Journey through a mesmerizing array of board games inside this museum.

Inside the corridors of this flea market, visitors are sure to find some obscure and odd treasures.

Legends surround an ancient tree trunk riddled with nails for good luck.

A silly medieval mural preserved on the side of a Viennese house.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

Op-art architecture designed for happiness.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.