My university has a library with a large round hall/chamber where students can study. On the sides it is supported by the columns. Is there a special word in English for big round rooms covered by a roof?
It's a rotunda.
A round building or room, especially one with a dome.
But you should have heard the comments when I explained to some tourists that the Radcliffe Camera was 'the rotunda you can see in the distance' rather than 'the round building ...'.