Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

This large copper bolt represents the benchmark for measuring sea levels in most of Europe.

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

An important landmark in the history of algebraic logic.

This Irish museum in a historic 19th century market pays tribute to the glory of butter.

The colorful stairs are made with marble from the world's major quarries.

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

Touching this 18th-century Scottish philosopher’s toe allegedly conjures good fortune.

360° views of the city plus five floors of optical illusions and hands-on science.

The fountain marks the area where hundreds of accused witches were burned at the stake.

It may look like no more than a full-scale model, but every part of this full Space Shuttle stack had a working role in aviation history.

The world's third-largest crystal sphere has sat in the Penn Museum since 1927 with the exception of one outlandish theft.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

The fastest transatlantic ocean liner sat abandoned in a Philadelphia shipyard for decades.

Ant sculptures march up the side of what used to be an iconic spot in punk rock lore.

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

Mural made of 100,000 pieces of hand blown glass, and one of the largest glass murals in the US.

A layered tribute to the work of mosaicist Isaiah Zagar.

The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

This beloved marketplace mascot poops money and grants good luck.

The first American department store, and home to the largest operating musical instrument in the world.

The sounds of the world's largest fully functioning pipe organ dazzle shoppers at a Philadelphia Macy's.

This elaborate towering structure was once famed for its revolutionary height.