Teotihuacan, the ruins of which are located near Mexico City, was one of the largest and most complex cities in the world during the first millennium AD. Although this mask shares features common to others from the city—a broad forehead, prominent nose, receding chin, and widely spaced cheekbones—it is subtly unique, indicating that it may represent a stylized portrait. Tied to wooden armatures adorned with feathers, jewelry, and garments, such masks were displayed in residential compounds and temples where they were the focus of rituals commemorating ancestors who acted as intermediaries between the living and the deified forces of nature. An older, recut stone mask was covered with mosaic tiles made from the inner layer of spondylus shell imported from the Pacific coast. The use of this exotic material suggests the far-reaching power, authority, and wealth of Teotihuacan. Spondylus was also considered sacred, associating this mask and the individual it honors with the generative power of lakes, rivers, and the sea.