This cathedral dedicated to Louis IX, sainted King of France, holds many secrets.

This Roman monument is surrounded by more recent construction, offering a stark contrast between ancient architecture and the modern urban landscape.

A memorial dedicated to the victims of the Columbine High School shootings.

Next to the Leaning Tower of Pisa is a cemetery home to ancient sarcophagi and disturbing murals.

A quirky mausoleum celebrated once every five years with young dancing girls, widows, a tax man, and more.

In a small Japanese garden off a busy Denver street, a memorial to a brave, principled politician.

A prehistoric rock shelter that's literally in someone's backyard.

This massive home was constructed by one of the greatest conservationists in Colorado history.

A small side chapel in Santa Fe's basilica is home to the oldest statute of the Virgin Mary in North America.

One of the oldest seagoing boats in the world can be found at the Dover Museum.

This Hawaiian cattle ranch acts as a museum devoted to the island cowboys that predate the wild west.

The famous aviator's final resting place is a study in natural beauty.

Take shelter from Hawai'i's tropical heat under the massive canopy of largest Banyan tree on the island.

A cooled lava flow from the Haleakalā volcano formed these surreal-looking columnar basalt structures.

Inside, visitors are treated to the rich history of sugar farming and its impact on Hawaiian society.

This popular cave pool is truly magical, despite the crowds.

A wonderfully eccentric Victorian-era museum and library.

A tribute to Loveland’s most famous sweethearts, who helped spread cupid’s message to millions.

This enormous "cloth of the conquest" depicts the Norman invasion of England in mind-blowing detail.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

An enthusiastically interactive mining museum that won't let black lung ruin the fun.

A seven-story 1920s mausoleum outside Denver houses thousands of remains.

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