If you visit Tokyo, you should not enter this building during your stay. Tokyo Metropolitan Police Department's headquarter is located close to Imperial palace's Sakuradamon gate and a few steps away from Tokyo Metro Yurakucho line's Sakuradamon station. Therefore TMPD is called Sakuradamon as like London's Metropolitan Police Service is called as Scotland Yard.
TMPD covers entire Tokyo metropolis including Tama district, Izu islands and Bonin islands; Ogasawara islands. It may be mistakenly recognized as headquarter of entire Japan or counterpart of FBI. However, National Police Agency is the governing body of all prefectural police departments including TMPD. NPA send their employees as high rank officers to prefectural police departments.
TMPD has 102 police stations, more than 45000 officers and staffs and 826 Koban(police boxes). Which means TMPD is the one of the largest police forces in the world. It is rumored that TMPD has bad relationship with neighboring Kanagawa Prefectural Police Department.