The mineral springs in this area played an important role in the history and development of the park. Between 1891 and 1902, the Parks Commission developed the park with the springs as a highlight. During that period, more than 20 different springs were identified, including sulfur, magnesia, iron, and naturally carbonated soda springs. To protect and identify them, tunnels were dug into the hillside and craftsmen built the grottos and fonts found here. Masons created the stone grottos using native rock collected from the canyon, and their intricate patterns and styles reflect the formality of the period. The popularity of the springs and the surrounding park led to the construction of bath houses, where spring water was piped to holding tanks, heated, and used in tile tubs. The large basin-type grottos are often mistaken for baths, but they are not tubs. As development continued, the park became popular as a health resort, and from 1892 to 1902, eleven local medical doctors certified that the waters were beneficial and recommended them for kidney and stomach troubles, rheumatism, and malarial afflictions.