The Nemi barges built by Caligula, were about 230 feet (70m). These are the largest Roman ships ever recovered, and it is a real pity they were destroyed in WW2. If we take this paper which argues for treasure ship being 'only' 200-250 feet. Then, the Romans and Chinese built similarly large ships.

The Greeks of the 2nd and 3rd century also might have built some massive ships. The Tessarakonteres, Thalamegos and Leontophoros are all claimed 300 foot plus wooden ships. The Tessarakonteres is thought to have been a catamaran, with 40 banks of rowers (it's name means 'forty-rowed'). Estimates of manpower would have 4000 oarsmen, with 2000 in each of the two hulls and either 300 or 600 oars. The two internal sides of the hulls could have had oars! However there is a limit to the usefulness of super-sized wooden vessels, especially caused by the forces of differential pressures from surface waves. Without metal bracing the anything approaching 300 feet of wood isn't sound for sailing in open waters.

Similarly the Chinese built even larger 'tower ships' (lou chuan) as riverine mobile naval fortresses. It is reported by Joseph Needham some of these massive fortresses were 1000ft long, although I would place the majority them closer to the 300-odd feet of similar giant vessels. Lou chuan were used in the Battle of Lake Poyang but were ultimately defeated by a smaller naval force using fire ships.

To wrap up, there is a limit to the useful length of a massive, unreinforced wooden vessels. That limit has been approached by any number of large naval powers of antiquity, but these ships weren't much more than vanity projects.