History
The Hibiya Line platform opened on 29 August 1964 after a rushed two-year build aimed at the Tokyo Olympics; the soft ground forced contractor Hazama to invent a "gap-caisson" pneumatic-caisson method that became a template for later subway construction. The Chiyoda Line platform followed on 20 March 1971, and Toei's then-Line 6 platform (renamed the Mita Line in 1978) opened on 30 June 1972. Cross-platform transfer with the Yūrakuchō Line at the adjacent Yūrakuchō Station was inaugurated when that subway line opened on 30 October 1974. Tokyo Metro inherited the Hibiya and Chiyoda Line facilities on 1 April 2004, and PASMO acceptance began on 18 March 2007.
History summarized from Japanese & English Wikipedia · last reviewed 2026-05-18.
Notes
Hibiya was originally to take the Imperial Palace's name, but the government and Imperial Household Agency refused, and planners fell back on the adjacent public park.