beast

Ambiguous tag. Use monster when it comes to non-animal, menacing-looking one.

• An animal, especially a large, ferocious or dangerous four-footed one.
• Any ferocious, powerful, large creature.
• A person who behaves in a violent, ruthless, antisocial or uncivilized manner.
• (slang) Anything regarded as larger or more powerful than one of its normal size or strength.

That is a beast of a stadium.