Bruegel painted this subject at least three times; we still possess two of the works. The "Big" Tower hangs in Vienna, the "Little" Tower in Rotterdam.
The Christian tradition interprets the tower, which was intended to reach up to heaven, as a symbol of hubris, of arrogance. In the picture from Vienna, it is King Nimrod, and thus the worldly potentate, who is the target of criticism. Here, in the Rotterdam painting, an almost invisible church procession is ascending the ramps: Bruegel is criticizing the Catholic Church.