PRINCETON, N.J. (AP) — Princeton University students often refer to the Ivy league campus as “the bubble.”

The school will soon have its own bubble installed over the football field during the winter after an anonymous donor contributed $3.5 million.

The climate controlled bubble will allow Princeton to use Powers Field year round.

Construction will start in the spring and it is expected to be ready for use at the end of the 2017 football season.