The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

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

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

This grand gothic brewery has been pumping out suds for over a hundred years.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

A small token of gratitude from freezing cold journalists who were given a warm haven while covering JFK's inauguration.

Amid the sprawling Defense Intelligence Agency Headquarters is one of Washington's least accessible museums.

This restaurant has been a haven for D.C.'s LGBTQ community since the 1950s.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

Home to a vast and influential collection of Shakespeareana.

Largest Roman Catholic church in North America.

The iconic Chicago sculpture hides a beautiful and easily overlooked plaque on the backside.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

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.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

A temple to modernity, tucked away amid Barcelona's more well known museums.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

Mountain where Jesus was first tempted by the Devil.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

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.