When Spanish conquistadors arrived in the Americas, they were often more interested in finding gods to conquer and treasures to take than in exploring the natural wonders of the land. Yet, in the heart of what is now the state of Puebla in Mexico, there lies a monument so massive that it was once mistaken for a simple green hill. This is the Great Pyramid of Cholula, hidden beneath the church of Nuestra Señora de los Remedios. For centuries, it was not recognized for what it truly is: one of the largest human-made structures ever built. The Great Pyramid of Cholula, also known as Tlachihualtepetl in the Nahuatl language, is estimated to be around 4.45 million cubic meters in volume—more than double that of the famous Giza pyramid of Khufu. This staggering structure was built over nearly a thousand years, with at least six layers of construction added by different Mesoamerican civilizations, including the Olmecs and the Teotihuacans. Despite its size, it has remained largely hidden beneath the church and its surrounding vegetation, which have helped conceal its true nature from view. The church itself, Nuestra Señora de los Remedios, has stood on the site since the 16th century. Though it appears unremarkable from the outside, it is built on the summit of the pyramid. The structure has been rebuilt multiple times, with its most recent reconstruction in the 19th century giving it its current neoclassical appearance. The hill beneath it, however, is no natural formation—it is the result of an immense construction project that spanned centuries. It was only in the early 20th century that construction work uncovered hints of this ancient structure, revealing the scale of the monument beneath the church. Since then, archaeologists have explored the site through a network of tunnels, uncovering parts of the pyramid’s layers and finding evidence of staircases, walls, and decorative elements. However, the presence of the church and the site’s continued use as a religious and cultural center have prevented a full excavation. Researchers are now working carefully to study the structure without disturbing its sacred and cultural significance. This balancing act reflects the broader challenges of Mexican archaeology, where the past and present often coexist in complex ways. The Great Pyramid of Cholula, though hidden from view, remains a testament to the ingenuity and persistence of ancient civilizations.