It was an experiment to prove that glacial boulders and rocks can be used in constructions and dwelling.

This stone tower in a small town's graveyard looks as though it would be more at home in a fairy tale.

Oldest church in the United States that is still in continuous use.

This castle constructed in 1928 was crafted from drawings of Lismore Castle in Ireland.

A unique columnar residence built in the 19th century.

The headquarters of one of the world’s longest-running humor magazines bears a noticeable resemblance to a head wearing a Prussian helmet.

This tea house was a hand-built gift from Boulder's sister city in Tajikstan.

A slice of central Asia in the middle of Berlin.

This psychedelic tromp l'oeil seems to be beckoning drivers to crash into a wall.

The Master of Magnetism dominates the walls of a scrap metal yard to keep graffiti artists at bay.

Long hidden under grime, the politically radical murals of a little known Yugoslavian master are finally getting their due.

A tribute to the pop culture icon overlooks this Washington D.C. intersection.

This famous church is adorned by a mural commemorating the independence of Vatican City.

Every year, the colorful murals of Montreal get a complete makeover.

This giant mural of Santa Muerte in downtown São Paulo reminds passersby of their own mortality.

South Philadelphia is home to Keith Haring's only surviving in situ collaborative public mural.

A collaborative art project that transformed a neighborhood in NYC's Queens.

A gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

This apartment building designed by a notable Washington D.C. architect housed the Qing Dynasty's Legation.

Where the U.S. government kept its actual treasure, before Fort Knox.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.