[1] The Siete Luminarias are low-rimmed volcanoes, or maars, with steep-sided, flat-bottomed central craters up to one kilometer in diameter.

The Bajío is in the basin of the Lerma River, which flows from east to west to the north of the volcanoes.

Four craters – Rincón de Parangueo, San Nicolás de Parangono, La Alberca, and Cíntora – were formerly home to crater lakes, but over-extraction of groundwater has caused all these lakes to dry up.

[6] In 1997 Siete Luminarias was declared a natural monument by the government of Mexico.

It covers an area of 89.28 km2 to the south, west, and northwest of the city of Valle de Santiago.