One of the largest underground systems runs under Canada's largest urban center.

Go inside the house that inspired L. M. Montgomery to create one of literature's most beloved heroines.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

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

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

The oldest cemetery in New Orleans, resting peacefully for over 200 years now.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A minotaur, a labyrinth, and a dubious restoration pull in visitors from around the world.

The hallucinogenic center of the ancient world.

Monasteries on rock pillars, once accessible only by frayed ropes.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

The final resting place of the great navigator, or maybe his brother.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

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

A little sculpture with a large wardrobe.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

Carvings in Turkey's Marble Road may have directed ancient Romans to a hidden brothel.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A marvel of Byzantine engineering under the streets of Istanbul.

Roman ruins top white travertine terraces formed by ancient hot springs.