This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

This narrow path was cut right into a French mountainside to feed the country's early naval expansion.

Located in the house where Gustave Flaubert was born, this odd museum has more to do with medical grotesquery than the Western novel.

This stunning French estate was so lavish that it landed its original owner in jail for the rest of his life.

The world's largest reflecting pool is just two centimeters deep.

The great Italian Renaissance painter was laid to rest here in the Chapel of Saint-Hubert.

An icy lake tucked among jaw-dropping alpine panoramas.

Nicknamed the "Museum of Horrors," this French anatomical collection has been fascinating visitors for over a century.

This crumbling, graffiti-covered mansion sits tantalizingly within reach of the proletariat who frequent a public park.

A public park off the beaten path with a beautiful waterfall and 13th century Cistercian abbey.

A tiled, multi-level garden of survival in Lyon.

A mosaic-tiled house built by graveyard sweeper Raymond Isidore.

A chapel on a volcanic core, marking the end of a successful journey.

A self-built mosaic house and sculpture park.

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

This stunning natural double arch, the largest in the Alps, went undiscovered until 2005.

Museum in a swimming pool where the water still flows.

An art world insider finds himself battling for his artistic home.

The world's tallest bridge is also possibly the most elegant.

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

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

Air Force Academy Chapel made of 100 identical tetrahedrons works to inspire those of all religions.

The encased skull that is widely believed to belong to St. John the Baptist.

Beautiful carved tunnels.