This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

Press 1 for knock-knock jokes.

A Guinness World Record-holding social enterprise whose shows don't shy away from heavy themes.

This rowhouse doubles as one of the most photographed spots in the nation's capital.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

This piece of early engineering is rather unknown despite its location in the heart of Madrid.

The oldest natural history museum in western Canada houses more than 5,000 vintage botanical and zoological specimens.

A stone marker and sculpture in the city of Riga stake a claim for the very first community Christmas tree.

Stone markers on the campus of Gallaudet University commemorate a peculiar school tradition.

This Khmer temple is named after a young woman who sacrificed herself to protect the city from a disastrous deluge.

This modernist bridge highlights the bear as a symbol of Madrid.

Shrapnel scars and bullet holes from the Spanish Civil War can still be seen in this monument to Spanish doctor Federico Rubio.

An exhibition devoted to the life (and posthumous taxidermy form) of the last known representative of the Pinta Island Tortoises.

Meant to resemble a massive tree, the building is the best example of Spanish organicist architecture in Madrid.

Explore a remarkable 35-hectare sculpture garden located an hour outside of Lisbon.

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

A precursor to Taro Okamoto’s iconic Tower of the Sun.

A unique, time-transcending work of art depicting the progress of trade in Singapore.

Built to celebrate the glory of a new queen, this forgotten monument has moved around Madrid three times, reflecting 200 years of political whims and city redevelopment.

A window into a long-lost world, these colorful tiles advertise a long-defunct range of purgative teas, harmless smokables, and diarrhea cures.

The only labyrinth within the city of Alexandria.

Enjoy dishes that founding fathers once ate at this Colonial Williamsburg pub.

This neon blue river gets its color from a unique mix of bacteria and volcano minerals.

Evidence of a long-ago crush remains scratched into the glass at this historic Maryland House.