Although the archaeological (考古学上的) discovery of Machu Picchu came nearly a hundred years ago, historians are still unsure (不肯定的) of the function of this ancient Inca (印加人，古代秘鲁土著) citadel (堡垒).
The earliest Maya (玛雅) began to settle the dense (浓密的) rain forests of southwestern Mexico and Guatemala (危地马拉) some 3,000 years ago. For nearly 1,400 years, settlements arose throughout the region, with some, like Tikal and Palenque (shown here), expanding into large, vibrant (充满活力的) city-states.
Myth, folklore, mystery, and intrigue surround the ancient city of Troy (特洛伊) like no other ruin on Earth. Once thought to be purely imaginary, a prop in Homer's epic poem The Iliad (《伊利亚特》), excavations (被发掘之地) in northwestern Turkey in 1871 eventually proved that the city indeed existed.
Over centuries of study, archaeologists (考古学家) have discovered many truths about the famed Stonehenge (巨石阵) monument in southern England. But despite these advances, the basic questions of who built this iconic (图标的) structure and why have remained unanswered.
More than 600 cliff (悬崖) dwellings made by the ancestral (祖传的，祖先的) Pueblo people, also known as the Anasazi, are scattered (撒播，驱散) throughout Mesa Verde National Park in Colorado (shown here).