In the late Edo period, the present-day Uchiwaisaichō area was a part of the Hibiya area with many daimyo's mansions and was located within the outer moat of the Edo Castle. Uchisaiwaichō, literally meaning "Inner Saiwai District," is considered to be named after its location between Saiwaibashi Bridge (幸橋 Saiwaibashi?) on the Outer Moat and Saiwai Gate (幸御門 Saiwai-gomon?).
After the Meiji Restoration, the term "Uchisaiwaichō" was introduced as a neighborhood in Tokyo.
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- Kroll Inc. (NBF Hibiya Building)
- NTT Communications
- JFE Steel
- Shinsei Bank
- Ernst & Young ShinNihon LLC
- The Tokyo Electric Power Company
- Fukoku Mutual Life Insurance
- Mizuho Bank (Mizuho Bank Uchisaiwaichō Head Office Building)
- Imperial Hotel
- "Office locations." Kroll Inc. Retrieved on 14 August 2011. "Tokyo 24/F NBF Hibiya Building, 1-7 Uchisaiwaicho 1-chome Chiyoda-ku Tokyo 100-0011 Japan" "Tokyo (Kroll Ontrack) 24/F NBF Hibiya Building 1-7 Uchisaiwaicho 1-chome Chiyoda-ku 100-0011 Japan"
- "Northeast Asia." China Airlines. Retrieved on August 30, 2011. "Tokyo 8F, 1-2-1, Uchisaiwaicho, Chiyoda-ku, Tokyo, Japan"
- "会社概要." Yamato Life. February 5, 2005. Retrieved on January 20, 2010. "所在地 〒100-0011東京都千代田区内幸町一丁目１番７号"