Signed into law in 1906, the Antiquities Act authorizes presidents to declare national monuments on federal lands to protect landmarks, structures, and “objects of historic or scientific interest.” In the mid to late 1800s, archaeology and anthropology played a significant role in the formation and passage of the Act, particularly in the Southwest, where there was an urgent need to protect archaeological sites from exploitation. While the Antiquities Act has played a crucial role in cultural and natural conservation efforts for 120 years, it has taken a precarious position in the modern legal landscape as recent challenges and shifting judicial interpretations question the scope of presidential authority. These issues reveal how the Antiquities Act continues to influence contemporary debates over conservation, resource use, Indigenous co-stewardship, cultural heritage, and the future of public lands.