A library and museum dedicated to typography.

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

An Industrial Revolution-era public work that purified water using nothing but sand.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

Home to items never before seen by the public.

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

This Parisian café sticks almost exclusively to an ethos of reuse.

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

Notorious artist squat renovated into legal studios.

Abandoned railway line circling the city of Paris.

Once a thriving business district, this former shopping area is now an urban ghost town in the heart of the city.

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

Crammed into a Baltimore row house is an oddities shop that sells everything from skulls to dead insects.

This free, take-a-book shop seems like a trick but isn't.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

The national park was once a plantation estate.

A historic neighborhood church is reborn as a psychedelic arts collective.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

This 19th-century church is now a popular roller rink.