Detail of the Hieroglyphic Stairway of Copn, an ancient Maya city in modern-day Honduras. Source: Wikimedia Commons.The American continents boast ancient wonders that continue to captivate experts and enthusiasts alike. These enigmatic sites reveal the ingenuity of civilizations long before the arrival of Europeans. They also raise important questions about belief, power, and survival.These are six of the most extraordinaryand the most mysteriousancient wonders of the Americas.1. The Pyramid of the SunThe Pyramid of the Sun at the archaeological complex of Teotihuacan in Mexico. Source: National Geographic.In the ancient city of Teotihuacan, near modern-day Mexico City, the Pyramid of the Sun towers over the landscape. Built around 200 AD, the pyramid measures over 200 feet tall and nearly 700 feet wide, making it one of the most significant structures in the ancient Americas.Excavations have revealed a hidden tunnel and chamber beneath the pyramid filled with offerings and sacrificial remains. These discoveries suggest it once served as a shrine or royal tomb. The pre-Aztec civilization that built Teotihuacan, as well as the reasons the city was abandoned by the 7th century, remain some of Mesoamericas greatest mysteries.2. The Nazca LinesAerial photograph of the Tree geoglyph of Nazca in Peru. Source: Diego Celso/Wikimedia Commons.Across 200 square miles of Perus arid plains, hundreds of lines and geoglyphs form the enigmatic Nazca Lines. The Nazca culture of ancient Peru etched the images into the earth nearly 2,500 years ago. Animals such as hummingbirds, monkeys, and killer whales appear alongside sprawling spirals and geometric figures.The exact purpose of these massive drawings remains unknown. Leading theories suggest they aligned with astronomical events, marked important sites, or functioned as appeals for rain in the dry climate.3. Cliff PalaceThe Ancestral Puebloan Cliff Palace at Mesa Verde National Park in Colorado. Source: National Park Service.High in the cliffs of Mesa Verde, Colorado,lies Cliff Palace, the largest known dwelling of the Ancestral Puebloan people. Constructed in the 13th century, Cliff Palace comprised 150 rooms and 23 ceremonial kivas, housing a population of approximately 100 people.Just decades after its construction, the cliffside settlement was left empty. While archaeologists dont know for certain, a prolonged drought likely forced the residents relocation.4. TiwanakuThe Kalasasaya Temple at Tiwanaku in Bolivia. Source: Wikimedia Commons.Near Lake Titicaca in Bolivia, at an elevation of more than 12,000 feet above sea level, the city of Tiwanaku flourished during the first millennium AD. Its monumental structures include the Akapana pyramid and the Kalasasaya temple, home to the famous Gate of the Sun.What sets Tiwanaku apart is its extraordinary stonework. Blocks weighing over 100 tons were cut and precisely fitted without the use of mortar. How the indigenous pre-Inca people of Tiwanaku achieved such feats, and why their city ultimately fell into decline, both remain a mystery.5. CahokiaCahokia Mounds World Heritage Site. Source: Wikimedia Commons.Almost a thousand years ago, the city of Cahokia thrived across the river from modern-day St. Louis, Missouri. Cahokia was the most significant urban settlement of the Native American Mississipian culture, boasting a population that rivaled that of medieval London.Cahokias 120 earthen mounds, including the 14-acre Monks Mound, functioned as ceremonial and political centers. The Cahokian Mounds are considered the largest pre-Columbian earthen construction in the Americas north of Mexico.While no written records survive from the original inhabitants of Cahokia, archaeologists have uncovered a solar calendar and evidence of human sacrifice on the site. By the 14th century, the city was abandoned. Its reasons for collapse remain unclear.6. CopnCopns Hieroglyphic Stairway. Source: Wikimedia Commons.In western Honduras, the ancient Maya city of Copn was ruled by a line of kings beginning in the 5th century. Copn stood out for its achievements in sculpture, including richly decorated temples and plazas. Most famous is the citys aptly-named Hieroglyphic Stairway. With over 2,000 glyphs charting the citys history, it is the longest known Maya inscription.By the 9th century, the once-flourishing city had fallen into decline, possibly due to factors such as environmental degradation, overpopulation, and political instability.