Coming to you now, from Seahaven Island, enclosed in the largest studio ever constructed and, along with the Great Wall of China†, one of only two man-made structures visible from space, now in its thirtieth great year, it's The Truman Show!
Announcer, The Truman Show
It contains a small town, a sea, land beyond the town. But Truman almost reaches its edge during his first attempted escape.
So how big is the studio?
Is there any source that gives a size, or does it come down to measuring and estimating?
† That the Great Wall of China is visible from space is a common misconception, here repeated by the announcer in the movie.