This overlooked, beautiful convent hides an original Hieronymus Bosch among its many treasures.

Arguably the best example of an authentic Dutch windmill in the United States, rivaling its counterparts in the Netherlands.

One of the best examples of the modernist movement in Madrid.

This Big Sur waterfall drops 80 feet directly into the Pacific Ocean, and inspired the hillside house up top.

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

Long tunnels run under the ancient chariot racing circuit to the tower.

Sky ships, planes, and portraits left as unique tokens of hope and thankfulness.

An architectural oddity hides in plain sight on this iconic London bridge.

Every day a troupe of pampered water fowl walk the red carpet to their favorite fountain.

A trailblazing sovereign nation tucked in the American state of Wisconsin.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

This sculpture meant to honor the bravery of the Indigenous Mapuche people of Chile proved controversial.

European castle ruins in an American state park are actually the product of death and grief.

"the sweltering inhabitants of Charleston and New Orleans, of Madras and Bombay and Calcutta, drink at my well . . . The pure Walden water is mingled with the sacred water of the Ganges."

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

The attic of a four-century-old canal house hides a clandestine church.

Originally conceived as part of a proposed Arizona State Capitol building in the 1950s, this structure built in 2004 stands as a monument to the architect's legacy.

The hotel where Martin Luther King Jr. was shot is now a museum dedicated to his work.

The blinking light atop the iconic landmark has been sending secret messages for decades.

The world's largest collection of materials relating to lesbian history is housed in a Brooklyn townhouse.

New York City's only radical feminist independent bookstore.

A circus of light and sound forms a sensory ode to an iconic train that will never pass through town again.

The ruins of a former sanctuary for elite Aztec warriors.

The ruins of an ancient city built by Mayan traders is centered around a temple of a sacred feathered serpent deity.