The ku derives its name from Chiyoda Castle, also known as the Edo Castle, located in the center of Chiyoda City. Edo Castle was the central government of Japan during the Edo period (1600 A.D. - 1867 A.D.) and after. In 1878, the Japanese government divided Tokyo into 15 cities; then in 1947, Kojimachi and Kanda cities were merged to form Chiyoda City (Chiyoda-ku). The Imperial Palace is a prominent feature, taking up over 10% of the ku's land mass.
Chiyoda-ku also known to tourists and tech junkies as the location of Akihabara.
Within Chiyoda-ku are many big train stations, most notably Tokyo Station, which offer access to nearly all major train and subway lines.