Akasaka Hikawa Shrine
Akasaka Hikawa Jinja (赤坂氷川神社), a Shinto shrine located in Akasaka and is also close to Roppongi, is where the primary spiritual guardian of Akasaka district is enshrined.
It was founded in 951 according to one legend. Another says it was established in the late 7th century. All Hikawa shrines, including this shrine, are spiritual branches of Omiya Hikawa Shrine in Saitama City, Saitama Prefecture.
Though this shrine, too, was bombard in WWII, its core buildings, constructed in the Edo period, managed to avoid being destroyed.
The Akasaka Hikawa-sai, the Annual Grand Festival of the shrine, is held in mid-August but fully conducted only in odd-numbered years.
It is an 8-min walk from Chiyoda Line Akasaka Station, Hibiya Line & Oedo Line Roppongi Station, and Nanboku Line Roppongi-icchome Station, respectively (all of them are subway lines).
Shaden, constructed in 1730, is the main building of the shrine composed of Haiden, Heiden, and Honden. Haiden is where you offer prayers, Honden is where divinities are enshrined, and Heiden is the building which connects these two.
Akasaka Hikawa Matsuri
The Akasaka Hikawa Matsuri (赤坂氷川祭), the annual grand festival of this shrine, is held in mid-August. Every year, there're joint processions of dashi floats and some mikoshi (portable shrine) for consecutive three weekend days. For details about this event, see the article on the Akasaka Hikawa Matsuri at Akasaka Hikawa Shrine.