Siege towers were not always that massive, but were used often enough by the Greeks and Romans. The largest one we know of was the helepolis from the Siege of Rhodes, which was 40 meters tall and 20 meters wide. It’s a pretty impressive size (siege still failed though lmao).

https://en.wikipedia.org/wiki/Helepolis

On the wiki page there’s also an example of the naval version, mounted on two boats. The Romans attempted to use that type to take Syracuse (and failed - at least insofar as the siege towers were concerned).