The bridge above is the main bridge to the Imperial Palace. It appears on guidebooks and postcards and is arguably the most famous bridge in Japan – even a symbol of Japan. Most people, including the Japanese, call it Nijūbashi. But this is sort of a case of mistaken identity.
Let’s Look at the Kanji
Nijūbashi is actually a nickname. The correct name of the bridge is 正門石橋 seimon ishibashi main entrance stone bridge.
Folk Etymology 1
There are actually two main bridges to the Imperial Palace. The 正門石橋 seimon ishibashi main entrance stone bridge and the 正門鉄橋 seimon tetsubashi the main entrance iron bridge. When you stand in front of the stone bridge you can see the iron bridge behind it and it looks like there are two bridges.
Folk Etymology 2
When reflected in the moat, an illusion of two stone bridges occurs, hence a “double bridge.” Some old people actually refer to the bridge as ﾒｶﾞﾈ橋 meganebashi the “glasses” bridge because… well, it looks like a pair of glasses.
Those two stories are cute, but they’re not actually correct.
The Real Etymology
Edo Castle also had two bridges here, but the names were different. The stone bridge was a wooden bridge called 西之丸大手橋 nishi no maru ōtebashi “front bridge to the western compound” and the iron bridge was also a wooden bridge called 西之丸下乗橋 nishi no maru kejōbashi “dismount bridge to the western compound.”*
Nijubashi was actually the nickname of the kejōbashi (now the iron bridge), not the ōtebashi (now the stone bridge). The bridge was built in 1614 by the shōgun, Tokugawa Hidetada. The bridge had a secondary wooden support mechanism built underneath which made it a 2 level construction. Because of these two levels, it looked like there were two bridges. The nickname 二重橋 nijūbashi/futaebashi came to be used as it was quite a distinctive bridge.
When the imperial court moved into the castle in 1868 but the bridges remained. After the confiscation and destruction of the daimyō residences in Daimyō Alley and elsewhere, the old bridge and gate system was re-evaluated. The two bridges were chosen as the main entrances to Tokyo Castle (the Imperial Palace). The kejōbashi was torn down and replaced with an iron bridge in 1888. It was rebuilt again in 1964 to match the 新宮殿 Shin Kyūden the New Palace, which is the collection of shitty 60’s-looking buildings that litter the palace grounds.
The 大手橋 ōtebashi was also torn down and replaced with the famous stone bridge in 1887. Because of its modern style, it quickly became a very high profile bridge – especially with the demolition of Daimyō Alley and the encroachment of commoners to the inner moats (in the Edo Period most commoners probably wouldn’t have been able to get too close).
In the Meiji Period, since the old kejōbashi formerly known as Nijūbashi no longer looked like a double bridge, the new main bridge became associated with the name. All the strange folk etymologies started popping up then too. And even though the bridge is not formally referred to as Nijūbashi, the Chiyoda Line subway station in the area (built in the 1970’s) is called 二重橋前駅 Nijūbashimae Eki Nijūbashi Front Station. Today the area around the station and bridge is colloquially referred to as Nijūbashi or Nijūbashimae.
Here’s a video I did on Nijubashi years ago:
* I’m not sure if I’ve translated the term correctly because I don’t really understand the purpose of this particular bridge. 下乗 kejō means “dismount” as in “get off of a horse.”
Also, if you’re curious about what “maru” means, please have a look on my post about Marunōchi and Daimyō Alley.