While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

Before Nixon, "watergate" meant canals.

Washington's iconic carousel has a nice piece of Civil Rights history.

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

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

The oldest continuously operating fish market in the United States.

The national park was once a plantation estate.

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.

The narrowest house in America is seven feet of pure spite.

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

The best place in the world to buy tinned fish.

Portugal's National Pantheon has a history of curses, collapses and financial problems.

Elaborate tile work in this railway station tells the story of Portugal.

A hidden three-foot-wide house separates these two regal churches.