[V99]

A lot of them don't. They work in nondescript windowless buildings controlling all the airspace that isn't right above an airport.

There have also been trials done with "virtual towers" at smaller airports, using a bunch of cameras and with controllers remotely monitoring them and communicating.

[whycome]

And as far as I can tell, representations are still projected on a 2D screen. Air traffic using 3d projections might lower the technical bar for controllers? VR + AI seems inevitable.