Machu Picchu, Peru: This iconic Inca citadel sits high in the Andes Mountains, overlooking the Urubamba Valley.
Petra, Jordan: Nicknamed the "Rose City" for the color of the sandstone cliffs from which it was carved. Petra was the capital of the Nabataean kingdom from around 300 BC to 106 AD.
Ankor Wat, Cambodia: This massive temple complex in Cambodia is the world's largest religious monument.
The Lost City of Z, Amazon Rainforest: This legendary city has been the subject of much speculation and exploration for centuries.
The City of Ubar, Oman: This ancient city, also known as the "City of Incense," is mentioned in the Quran and is believed to have been a major center for the frankincense trade.
Kilwa Kisiwani, Tanzania: This island city off the coast of Tanzania was once a flourishing Swahili trading center.