Old Tokyo
Old Tokyo (Tokyo-1) is the former capital of Japan, the original city of Tokyo. Tokyo was destroyed on September 20th, 2000, seven days after Second Impact by a nuclear bomb as a result of post-Impact wars (it is not specified who launched this attack). The destruction of Tokyo resulted in the death of half a million people. By 2015, Old Tokyo is a mostly underwater ruins, due to subsequent global coastal flooding after Second Impact, with the dead city's skyscrapers jutting above the water's surface. It is a completely uninhabitable wasteland.
In Episode 07, this wasteland is used as a testing site for the giant robot, Jet Alone.
In Episode 08, the Angel Gaghiel drags Evangelion Unit-02 through the underwater ruins of Old Tokyo, crashing through submerged skyscrapers as they battle deep beneath the water's surface.