Elaboration: Modern-Day buildings are made of steel frames, concrete and glass (or Mostly I guess. Depends on the bulding) while Castles are full on Rocks and bricks way more durable than any building wall in comparison. A Modern Building simply isn't designed to survive sieges like Castles are, and Goku tore through that. And since Ki is directly proportional to one's physical strength (Or else we have crazy stuff like Cell facetanking Kamehamehas yet still have to block Goku's punches), Oozaru Goku also has range by going "I'mafirinmahlazarhBLARGH"
Although Zilla did it's feat relatively easily, so did Goku. So both are technically unquantifiably higher than Building level.
Calaca Vs wrote:
Goku takes this via better stats and range. I also think that an Oozaru is bigger than Zilla.
Zilla is officially 60m tall in 1998. Oozaru's height has no canon number and is inconsistent due to how toriyama drew it. However, lowscale estimates that Oozaru is at least 40m tall (10m less than Zilla) and more reasonable estimates put Oozaru at around 60-70m and larger estimates (in comparison to the castle) puts it well over 100m tall.
I'm not using later showings of great ape since Vegeta only clocks in at around 30-35m tall for some reason and Manga great apes are well over 200m tall while the Toei Oozaru from Father of Bardock special would be almost 3-4x larger than Kid Goku's Oozaru.