Edo Castle

Timeline

1. 1457

   Ōta Dōkan builds the castle

   Ōta Dōkan, retainer of the Ōgigayatsu Uesugi, raises a hilltop castle on the Kōjimachi plateau with a triple-bailey shijō / naka-jō / gai-jō layout.

2. 1524

   Later Hōjō take the castle

   Hōjō Ujitsuna of the Later Hōjō clan defeats the Ōgigayatsu Uesugi and brings Edo Castle into his Kantō network as a strategic forward base.

3. 1590

   Tokugawa Ieyasu enters Edo

   Granted the eight Kantō provinces after the Siege of Odawara, Tokugawa Ieyasu enters Edo on the first day of the eighth month, beginning the city's transformation into Japan's center.

4. 1603

   Edo shogunate and tenka-bushin

   Ieyasu is appointed Sei-i Taishōgun and founds the Edo shogunate. Large-scale tenka-bushin construction of Edo Castle begins, mobilizing daimyō nationwide.

5. 1607

   Keichō tenshu completed

   Designed by Tōdō Takatora with the tenshudai built by Kuroda Nagamasa, the Keichō-era tenshu is completed under Ieyasu — Edo Castle's first true monumental keep.

6. 1636

   Outer sōgamae completed

   Under the third shōgun Iemitsu, completion of the Sanada-bori closes the outer moat ring, finalizing Japan's largest castle complex of 15.7 km perimeter and 2,082 hectares.

7. 1638

   Kan'ei tenshu completed

   Iemitsu rebuilds the keep as the Kan'ei tenshu — five external stories and about 58 m in height, the tallest castle keep ever raised in Japan.

8. 1657

   Meireki Fire destroys the keep

   The Great Fire of Meireki burns both the Honmaru and the Kan'ei tenshu. On Hoshina Masayuki's counsel the keep is never rebuilt — only the tenshudai remains.

9. 1701

   Matsu no Ōrōka incident

   In the Honmaru's Matsu no Ōrōka corridor, Asano Naganori draws his sword on Kira Yoshinaka, igniting the chain of events behind the Akō rōshi vendetta of Chūshingura.

10. March 3, 1860

    Sakurada-mon Incident

    On the third day of the third month of Ansei 7, Tairō Ii Naosuke is assassinated by Mito rōnin just outside Sakurada-mon — a decisive shock accelerating the Tokugawa collapse.

11. 1868

    Bloodless surrender of Edo

    Through negotiations between Katsu Kaishū and Saigō Takamori, Edo Castle is handed over peacefully to the new Meiji government and renamed Tōkei-jō, then Kōjō.

12. 1873

    Old Honmaru palace burns

    A fire on May 5 destroys much of the surviving Edo-period architecture including the old Honmaru palace, hastening the shift toward a new imperial residence.

13. 1888

    Meiji Kyūden completed

    The Meiji Kyūden palace is completed on the former Nishi-no-maru, formally turning the old Edo Castle grounds into the modern imperial residence.

14. 1948

    Renamed Kōkyo

    The compound is officially renamed from Kyūjō to Kōkyo (Imperial Palace), placing the former Edo Castle grounds at the heart of the postwar monarchy.

15. 1963

    National Special Historic Site

    Designated as Kyū-Edo-jō-ato, a National Special Historic Site of Japan; the Honmaru, Ninomaru, and Sannomaru ruins gradually open as the Imperial Palace East Garden.

Detailed History

Edo Castle's origins reach back to 1457 (Chōroku 1 / Kōshō 3), when Ōta Dōkan, retainer of the Ōgigayatsu Uesugi under Uesugi Mochitomo, built a hilltop fortress on the Kōjimachi plateau during the Kyōtoku War. Contemporary records describe a triple-bailey shijō / naka-jō / gai-jō layout, with Dōkan's residence Seishōken in the inner core. After Dōkan was killed by his lord Uesugi Sadamasa in 1486, the castle passed to the Later Hōjō in 1524 (Daiei 4) when Hōjō Ujitsuna defeated the Ōgigayatsu line. In 1590 (Tenshō 18) Toyotomi Hideyoshi's Odawara campaign destroyed the Later Hōjō, and Tokugawa Ieyasu — newly granted the eight Kantō provinces — entered Edo on the first day of the eighth month. After his 1603 (Keichō 8) appointment as Sei-i Taishōgun, Ieyasu launched the tenka-bushin construction by which Edo Castle was reshaped at unprecedented scale. In 1606 (Keichō 11) tozama daimyō including Hosokawa Tadaoki, Maeda Toshitsune, Ikeda Terumasa, Katō Kiyomasa, Fukushima Masanori, Asano Yoshinaga, Kuroda Nagamasa, and Tōdō Takatora were assigned the outer-wall stonework, with Kuroda Nagamasa specifically tasked with the tenshudai. The Keichō tenshu was completed in 1607 (Keichō 12). Under Hidetada the Genna tenshu followed in 1622 (Genna 8), and under Iemitsu the Kan'ei tenshu in 1638 (Kan'ei 15). In 1636 (Kan'ei 13) the Sanada-bori closed the outer moat, completing Japan's largest castle complex. The Meireki Fire of 1657 (Meireki 3) burned both the Honmaru and the Kan'ei tenshu, and on the counsel of Hoshina Masayuki — Iemitsu's regent — the keep was never rebuilt. In 1701 (Genroku 14) Asano Naganori drew his sword on Kira Yoshinaka in the Matsu no Ōrōka, igniting the chain of events behind Chūshingura. In 1860 (Ansei 7) Tairō Ii Naosuke was assassinated by Mito rōnin just outside Sakurada-mon. With the 1868 Restoration and the bloodless surrender negotiated by Katsu Kaishū and Saigō Takamori, the castle was renamed Tōkei-jō, then Kōjō, and became the Meiji Emperor's residence; Kōkyo (Imperial Palace) followed officially in 1948. A fire on May 5, 1873 destroyed most of the Edo-period buildings; in 1888 the Meiji Kyūden palace rose on the Nishi-no-maru. That palace burned in 1945, and today's Imperial Palace buildings were rebuilt in 1968. The site was designated a National Special Historic Site as Kyū-Edo-jō-ato in 1963.

Cultural Significance

Edo Castle was the political nerve center of Tokugawa Japan for more than 260 years, and the era itself takes its name from this place. It holds Japan's highest cultural classification as a National Special Historic Site (Tokubetsu Shiseki), while the surviving Sakurada-mon, Tayasu-mon, and Shimizu-mon are nationally designated Important Cultural Properties. The alternate name Chiyoda-jō, recorded in Wikidata, comes from Chiyoda Ward — the modern administrative area covering the old Kōjimachi plateau. Its cultural footprint is enormous: the Matsu no Ōrōka incident of 1701 that triggered Chūshingura, the 1860 Sakurada-mon Incident, the 1867 Taisei Hōkan, and the 1868 bloodless surrender of Edo all unfolded within these walls. The castle appears across innumerable historical novels — Ryōtarō Shiba's Kaidō wo Yuku, Sōhachi Yamaoka's Tokugawa Ieyasu, Shōtarō Ikenami's Kenkaku Shōbai — and is a near-permanent backdrop of NHK's Taiga Drama. Strikingly rare in world terms, the compound still functions as the residence of the reigning head of state, embodying unbroken political continuity from the late medieval through the modern era. The Honmaru, Ninomaru, and Sannomaru ruins, opened freely as the Imperial Palace East Garden, draw more than 1.5 million visitors annually as a rare downtown space where Japan's path from Sengoku to Meiji can literally be walked.

Architectural Details

Edo Castle is a renkaku-style hirayama-jiro centered on the Honmaru and ringed by Ninomaru, Sannomaru, Nishi-no-maru, Kita-no-maru, Fukiage, and Nishi-no-maru-shita baileys, enclosed by inner and outer moats in a triple sōgamae layout. The outer perimeter ran roughly 15.7 km for some 2,082 hectares, five times Osaka Castle's area. The Kan'ei tenshu of 1638 stood five external stories with five floors plus a basement, reaching some 58 m with the tenshudai — Japan's tallest castle keep ever. After it burned in 1657 it was never rebuilt, leaving only the granite kirikomi-hagi tenshudai (about 11 m high, 41 m by 45 m). The castle held 38 gates at its peak; surviving Sakurada-mon, Tayasu-mon, and Shimizu-mon are Important Cultural Properties, while Ōte-mon, Hirakawa-mon, Kitahanebashi-mon, and Inui-mon are reconstructed. Stonework drew on Izu volcanic rock and Seto Inland Sea granite, hauled by sea under tenka-bushin assignments. Higo-school masons under Katō Kiyomasa delivered precision kirikomi-hagi joinery throughout. Features include sangi-zumi corner interlocking, polished kagami-ishi mirror stones, and oversized Edo-cut blocks broadcasting daimyō prestige. The inner moat runs 8.5 km at depths up to 8 m, forming Japan's most formidable double-moat defense. The 1968 Imperial Palace buildings on the Nishi-no-maru are reinforced concrete in traditional wooden idiom.