eHow has a great history of Japanese lanterns, including their importance in religion:
“Embracing Buddhism, the Japanese use of stone lamps called Ishidoro, originally served to light temples and later marked the grounds of these shrine areas. Stone lantern shapes were specific in meaning and became more worldly in use with the onset of the Japanese sacred tea ceremony. This national tradition came about when the Chinese introduced the hot beverage to this neighbor to the east. Lighting dark paths leading to the tea ceremonial hut, stone lanterns eventually moved into use in modern times as garden decorations.”
This stone lantern was one of a handful surrounding the Japanese tea garden in Golden Gate Park, San Fransisco, CA.