The Hale Solar Laboratory is a historic astronomical observatory in Pasadena, Los Angeles County, California, United States.

Built in 1923, it was the laboratory of astronomer George Ellery Hale (1868-1938), a pioneering figure in the development of the discipline of astrophysics in the United States.

The stem of the T consists of the telescope tower and Hale's library/office and living area, while the top portion of the T historically housed electrical and ventilation equipment.

The main entrance is at the base of the tower, set in an arch above which is an incised bas-relief tribute to Akhenaten, the Egyptian pharaoh who worshipped the sun god Aten.

[5][6] The observatory was where Hale refined the spectrohelioscope, making it possible to perform detailed observations of the surface of the Sun.