One of the largest projects at Llano involved the construction and financing of the Llano Pantheon Mausoleum, which took place during the period of 1927 to 1929. The pantheon was designed by Sidney Lowell of Chicago and constructed of Bedford marble, a stone known for its endurance. Local architect, Joseph Champ Berry was the project supervisor. The project involved significant fundraising and advance sales of rooms and crypts to pioneers, including Colonel Herring, Mrs. Oliver-Eakle and Mr. and Mrs. E.W. Hardin. The Great Depression slowed sales and the collection of subscriptions. Mr. W. H. Fuqua, known as the father of the First National Bank of Amarillo personally advanced $62,000 to pay off the balance of the construction contract.
Two additions have been made to the Llano Pantheon. In 1949, an entrance was added to the building and a four-story tower was constructed on the east side, uniting the old and new wings. In 1961, the association launched another beautification project with the addition of a new 17-acre plot between the 1933 gate (which is near the administration building) and 27th Avenue. The Pantheon’s 1964 addition was constructed completely underground. It was designed by Sam McClesky of Atlanta, Georgia. John Hannon was associate architect. Floyd Richards was contractor.