The king of U.S. high points towers over every other peak on the continent.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

This expansive bridge in the Canadian wilderness was originally just built for friends.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

This Tibetan monastery has survived multiple attacks and is also a sky burial site.

The highest monastery in the world operates a tiny guesthouse with doors open to all.

The largest madrasa in Morocco once housed more than 900 students within its exquisite walls.

Fortune tellers, snake charmers, poets, and storytellers all gather on this historic square in Morocco.

Morocco's Argania trees are infested with nut-hungry goats.

This museum in the famously blue neighborhood of Sidi Bou Saïd showcases a traditional Tunisian lifestyle.

The ancient heart of Tunis is an enormous maze of narrow streets and alleyways.

Go inside to really appreciate this 500-year-old technological masterpiece.

A Milanese café entirely designed by the American director Wes Anderson.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

Legend says this sacred tree was a gift from goddess Athena.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

A stunning fusion of Ottoman and Fatimid architectural styles.

A marvel of Byzantine engineering under the streets of Istanbul.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

A beautiful mountaintop mausoleum devoted to a Montenegrin icon can't seem to make everyone happy.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

An ethereal glowing blue ocean cave in Croatia.

The largest and, arguably, most scenic fortress in Bhutan.

This giant Buddha statue has 125,000 smaller Buddhas hidden inside it.