The most accurate timepiece in the world.

Decades before the scandal, this staircase on the river was a literal "water gate."

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

Largest Roman Catholic church in North America.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

The oldest continuously operating fish market in the United States.

When it opened during the final years of the embargo, all the drinks and cigars were free.

The national park was once a plantation estate.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

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

A derelict bit of transportation infrastructure hidden in the woods.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

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

Home to items never before seen by the public.

The United States Capitol's former columns still stand.

This volcanic cave lake is essentially hard proof that Iceland is the most magical place on Earth.

Instead of solid circles, the stoplights in this northern Icelandic town have glowing red hearts.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

The bright red stripes streaking across the rocks are the star feature at this Icelandic waterfall.

This black church sits alone among a field of lava rock.

A sulfuric martian landscape that looks far better than it smells.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

A little-visited waterfall in an otherworldly landscape.