Legend has it that the keystone, known as 'Heso-ishi' (navel stone) in the eastern side of the main hall is from the foundation of the former main hall and it is said to be the center of Shimogyo.
本堂東側の要石（かなめいし）は、旧本堂の礎石と伝えられ「へそ石」とよばれ、下京の中心地であるといわれている。