Right outside of the Don Harrington Discovery Center sits a large steel structure. This monument is dedicated to helium, the gas that originally brought prosperity to Amarillo. At one point of time, Amarillo was the world's only commercial producer of helium. The monument is dedicated to the importance of helium in the building of Amarillo's economic development and growth as a city. The structure is also filled with time capsules from the 1960s.

Built by local millionaire/philanthropist Stanley Marsh III, Cadillac Ranch is easily one of Texas' most recognizable attractions. Eleven rusted, gutted-out Cadillacs are lined up and photogenically planted hood-first in the dirt. Unlike the pyramids, Stonehenge and other cultural landmarks, visitors are encouraged to bring spray paint and let loose on this monument. Every visitor to Amarillo should experience Caddy Ranch at least once.

Completed posthumously, this unique piece of art was the brainchild of Robert Smithson, a renowned American artist known for his provocative earthworks. Concerned with commercialism and art, Smithson strove to create an art form that could exist outside the confines of a gallery in a non-traditional viewing space. One of his last creations, the Smithson perished attempting to search for the perfect location for his next piece, the Amarillo Ramp. Inspired by his legacy, the piece was finished by his contemporaries, Richard Serra and Tony Shafrazi.