One of Frank Lloyd Wright's greatest—and favorite—architectural masterpieces was almost lost.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

A reversed traffic signal that was once violently misinterpreted as a statement on British-Irish relations.

An antique cemetery in New York, this land is home to any number of famed corpses.

The gravestone of the suffragist leader attracted extra visitors during the 2016 election.

The site of William McKinley's tragic assassination is only marked by an underwhelming boulder.

This unusual structure may be on its way to becoming a cultural landmark in Toronto.

A collection of more than 12,000 shoes, displayed in a building shaped like a shoebox.

The artwork commemorates the many ways 20th-century people perished while on the clock.

This massive, ancient stone was disassembled and then put back together again.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

Once used as a deterrent to drinking alcohol.

North America's oldest quarantine facility was built in response to Philadelphia's 1793 yellow fever outbreak.

South Philadelphia is home to Keith Haring's only surviving in situ collaborative public mural.

Visit a fourth-generation farm and museum dedicated to everyone's favorite fungi.

One of the largest underground systems runs under Canada's largest urban center.

Quite simply the largest tree in the world (by volume).

The "Seinfeld" diner.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.

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

Tucked in the back of a flower shop, its collection details the fascinating history of the Netherlands's iconic symbol.

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

These 20-foot sculptures will help guide you from the local train station to the local sculpture garden.

This Delaware River bridge is emblazoned with a catty slogan from a more prosperous time.