The University of Tokyo (東京大学; Tokyo daigaku), often abbreviated as Todai (東大), is the most prestigious university in Japan. Its main campus is in Hongo (Bunkyo). As far as I can tell, although there are guards at the gates, it can be entered pretty much freely.
Above, the Red Gate (赤門; Akamon).
Above, main gate.
Above, clock tower (Yasuda Auditorium).
Above, pond in Ikutokuen garden.