Halcyon is an unincorporated community of about 125 acres in San Luis Obispo County, California, just south of Arroyo Grande. It was founded in 1903 as a Theosophical intentional community and is th…Halcyon is an unincorporated community of about 125 acres in San Luis Obispo County, California, just south of Arroyo Grande. It was founded in 1903 as a Theosophical intentional community and is the home and headquarters of a religious organization, The Temple of the People. The Temple group was founded in 1898.