Equinox is a collection of images at the Salk Institute for Biological Studies, a scientific research institute in La Jolla, California, designed by Estonian-born American architect Louis I. Kahn, in collaboration with Mexican architect Luis Barragán. The building displays Kahn’s distinctive monumental and monolithic, concrete-based style, with a unique water feature along its smooth, travertine courtyard named the “River of Life.” Twice a year, on the spring and fall equinoxes, the setting sun aligns perfectly with this water feature, an event known as the “Salkhenge” sunset, a spectacle worth witnessing.