it was known as Line 11. Construction began in 1972 and the majority of the line was expected to open in 1975. However, the Teito Rapid Transit Authority did not have enough funds to build the line, which delayed its construction. On August 1, 1978, the first section of the Hanzōmon Line finally opened from Shibuya to Aoyama-itchōme, including through services with the Den-en-toshi Line. It was then extended to Nagatachō Station in September 1979. However, the next extension posed political problems, as the original plan had the line run directly under the Imperial Palace to Ōtemachi Station. TRTA decided to divert the route around the north side of the Imperial Palace, which required the construction of three new stations. An eminent domain battle erupted with landowners along the proposed route, which delayed the completion of the next stage of the line. Hanzomon Station opened in December 1982, and the full extension around the Imperial Palace, terminating at Mitsukoshi-mae, was not completed until January 1989. The line was then extended to Suitengu-mae in November 1990 and finally Oshiage in March 2003, the latter also enabling through service with the Tobu Skytree Line. The line, station facilities, rolling stock, and related assets were inherited by Tokyo Metro after the privatization of the Teito Rapid Transit Authority (TRTA) in 2004. The Ministry of Transportation recommended in 2000 that the line be extended to Matsudo by 2015. However, Tokyo Metro stated in its initial public offering that its construction operations would cease once the Fukutoshin Line is completed, which casts some doubt as to whether the Matsudo extension will actually be built. Notes a. Crowding levels defined by the Ministry of Land, Infrastructure, Transport and Tourism: 100% — Commuters have enough personal space and are able to take a seat or stand while holding onto the straps or hand rails. 150% — Commuters have enough personal space to read a newspaper. 180% — Commuters must fold newspapers to read. 200% — Commuters are pressed against each other in each compartment but can still read small magazines. 250% — Commuters are pressed against each other, unable to move. References External links Tokyo Metro website Lines of Tokyo Metro Railway lines in Tokyo 1067 mm gauge railways in Japan Railway lines opened in 1978 1978 establishments in Japan