Inground storage tanks are essentially safe structures and this is one of their foremost advantages. Convinced of the excellent properties of inground storage tanks, Tokyo Gas built the world's first 10, 000kl membrane-lined inground storage tank at the firm's Negishi Terminal in 1970. Since then, 46 inground tanks have been built altogether, from a minimum capacity of 650kl to a maximum capacity of 140, 000kl per unit. In the meantime, we have addressed wide-ranging technologies related to inground storage tanks. The research and development efforts have been reflected in the construction of large-capacity inground tanks. This paper focuses on the LNG inground storage tanks with the latest technologies, centering on our latest 140, 000kl inground tank, and then discusses the current state of the technology in this area. It also refers to the future trends such as the development of extra-large tanks.