The oldest operating Mississippi River–style steamboat still navigates the Ohio River.

This hidden jockey “walk of fame” celebrates the winning riders of the Kentucky Derby.

Amsterdam's narrowest house facade is a monument to 17th-century tax evasion.

A floating cat sanctuary on an Amsterdam canal.

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

Remnants of a 4th-century church with vivid medieval frescoes and ancient sarcophagi hide beneath this old basilica.

"We Seceded Where Others Failed."

A monument celebrating the idea of reaching inaccessible places.

Meet manatees face-to-face at this zoo for native species.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

This bridge was constructed from the rubble of the infamous Bastille.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

The first green space constructed on an elevated viaduct.

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

The Sun King's military models, saved from the Louvre.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

This strange bovine gargoyle is said to have been put in as a passive aggressive form of revenge.

Memorials at a Florence railway station remember the citizens who were deported from Italy and sent to extermination camps.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.