The Temple of the Feathered Serpent was the third largest pyramid in Teotihuacan. Although significantly smaller in size than both the Sun Pyramid and Moon Pyramid, it was one of the most elaborate monuments in the city. Manuel Gamio's excavations carried out between 1917 and 1922 (Gamio 1922 (1979)) revealed that the principal facade had been covered with carved blocks, including impressive three dimensional sculptures. The excavations by the Proyecto Arqueol?gico Teotihuac?n 1980-82 of the Instituto National de Antropolog?a e Historia confirmed that the facades on all four sides of the pyramid had been decorated with carved stones depicting the motifs discovered earlier by Gamio. These discoveries indicated that the construction of the monument - quarrying, transporting, arranging, and carving heavy stone blocks - represented a remarkably high energy expenditure of the state.