The Aztecs saw an eagle perched on a cactus as the sign that they should build Tenochtitlan. In the traditional founding story, the eagle held a snake in its beak while standing on an Opuntia, or prickly-pear cactus.
The Mexica people had been wandering in search of the place promised by their religious tradition. They recognized the omen on a small, swampy island in Lake Texcoco and founded Tenochtitlan there in 1325. The site’s difficult terrain did not prevent the city from expanding.
The Mexica enlarged the island and created farmland using chinampas, often called “floating gardens,” though these were engineered agricultural plots built in shallow lake environments. Tenochtitlan eventually became the capital of a powerful Mesoamerican state and one of the largest cities in the world when Hernán Cortés arrived in 1519.
The eagle, cactus, and snake remain central symbols of Mexico. The image appears on Mexico’s coat of arms and at the center of the national flag, so it is sometimes mistakenly described as merely a modern national emblem rather than an older Mexica foundation story.