Sources

• Maps and aerial photos: Geospatial Information Authority of Japan (GSI tiles). Today's pale map is shown underneath. Choosing "Aerial" under "Map | Aerial" switches today's side to GSI's latest aerial photos (taken in 2019 for the Tokyo 23 wards).
• Year: choose it from the years listed under "Map | Aerial" (in the top band on phones). The aerial photos were taken in these periods (all by GSI): 1940 = c. 1936–1942, 1947 = 1945–1950 (taken by the US military), 1960s = 1961–1969, 1980 = 1979–1983, 1990 = 1987–1990. The c. 1940 photos cover only the Tokyo 23 wards and appear when you zoom in. 1945 is not an aerial photo: it shows the burned areas marked on the Teito Kinbo-zu map.
• "Today | Past" bar at the bottom: move it to the left to show more of today's map, or to the right to show more of the selected year.
• Old map: Teito Kinbō-zu: Sensai Shōshitsu Kuiki Hyōji (Map of the Capital Area Showing Districts Destroyed by Fire in the War; Nihon Chizu, 1946 reprint), collection of the International Research Center for Japanese Studies（国際日本文化研究センター所蔵）. The old map is aligned to today's map by hand and may be off by about 50–125 m.
• Redevelopment projects: sources are listed for each project. Projects under construction or planned are mainly based on the urban redevelopment project pages of the Tokyo Metropolitan Government (in Japanese; the date of each source is shown). English descriptions of each project will be added later.
• Map library: MapLibre GL JS