"The buildings are huge."

Translation: Os edifícios são enormes.

[MarcoPerez1]

why doesn't os edificios são muito grandes work?

[Paulenrique]

muito grandes = very big. huge = enorme. Duo prefers more literal translations....

[Ricardo-Luiz]

I used "imenso" instead of "enorme". It should be considered, because both two words have the same meaning in Brazil

[saschambaer]

Is there a difference between edifício and prédio?

[Paulenrique]

They mean the same. Prédio is usually used in conversation and Edifício is what you see on the front of a building along with its name ;)