The tower is located next to Mitsui Honkan, the historical headquarters of the Mitsui conglomerate, designed by Trowbridge & Livingston and built in 1929. Mitsui Honkan was designated as an Important Cultural Property in 1998, and the Mitsui Tower project was subsequently designed and built in a complementary style. This is most visible in the exterior design of the lower levels of the tower. Mitsui Honkan was refurbished alongside the construction of Mitsui Tower, and now houses the Mitsui Memorial Museum in addition to a branch of Sumitomo Mitsui Banking Corporation.
