"Holy Wisdom" overlooks the city that became its namesake.

A striking symbol of the Bulgarian capital.

This once-derelict building is now one of the most beautiful bookstores in the world.

Romania's triumphal arch looks out over Bucharest.

Locals believe this abandoned ruin on the outskirts of Bucharest is haunted.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

A marvel of Byzantine engineering under the streets of Istanbul.

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

This Brazilian Lady Liberty is one of the few replicas that was actually made by the original designer.

Known as the "Finger of God," a dramatic rock formation resembles a divine hand extending towards the heavens.

A 125-meter long "tribute to the Brazilian people."

Eduardo Kobra’s breathtaking 32,300-square-foot graffiti wall took over Rio’s Olympic Boulevard.

One of the newest mosques in a city filled with thousands.

This center in the Rwandan capital supports women’s livelihoods while educating visitors about traditional cooking, craft making, and more.

Burial site of the world's most widely known researcher on the endangered mountain gorilla.

A deadly ancient portal to the underworld.

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

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