Old Tokyo maps online
Yahoo! Japan is featuring old Tokyo maps online (Japanese):
You can switch between maps of Tokyo from the Edo era (about 180 years ago), the Meiji era (about 120 years ago), the present, and satellite photos.
If you can read Japanese, it is amazing to discover what many famous places today were in the past. And you can understand that many mansions of daimyos (feudal lords) which were located in the center of Edo city were abolished at the end of the Samurai age and their lands were redeveloped into fundamental public facilities for a modern capital city such as government office buildings, military bases, universities, hospitals, business districts, parks and so on. It is one of the reasons why Japan could reform itself to a modern nation so quickly.
If you would like to know why there were so many daimyos’ mansions in Edo city, see this wiki article.
FYI, the lot for the Tokyo campus of the University of Tsukuba, the former Tokyo Higher Normal School, was a mansion belonging to MATSUDAIRA Yorinobu who was president of a government bureaucrat training institution, and a descendant of TOKUGAWA Mitsukuni’s younger brother. Tokugawa is also known as Mito Komon.
Enjoy some time travel!