Entire apothecaries are on display at this Lisbon museum, which explores the history of medicine.

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

An early Portuguese serial killer's head is alarmingly well preserved in a jar at the University of Lisbon.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Artistic tombs, monuments, and a beautiful "Hall of Fame" lurk inside this cemetery.

The odd depiction of the Virgin Mary and baby Jesus is rooted in the Catholic Church's eradication of Catharism.

Just across from the "Last Supper" painting is the famous painter's vineyard, a gift received for creating the masterpiece.

Small on the outside, big on the inside, this church is an astonishing act of visual deception.

Masterful ceramic fountain and map of the Pacific Basin.

The taxidermied remains of the "last wild grizzly bear in California" and of the symbol of the state of California.

America's oldest Italian restaurant is a San Francisco institution.

This turn of the century masterpiece has a mysterious goaty interloper.

This residential door allows San Francisco muggles a glimpse at the wizarding world.

A still functioning vaudeville carousel that has operated for over a century boasts a colorful menagerie and past.

Golden Gate Park's historic collection of plants.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

San Francisco's newly reopened hands-on science museum.

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A psychedelic labyrinth on the San Francisco bay.