a bank cannot be short! you don't say that a building is short. In addition, earlier in the course, short was not accepted for alacsony
Welcome to Duolingo. The woman is in the fridge. The duck is on the elephant. These chains are for my daughter. Where are the tall schools?
No, vannak (plural 3rd form) cannot used in this sentence. When it is about describing a property, the substantive verb does not necessary in present tense. E.g. ő katona ((s)he is a soldier), az ég kék (the sky is blue), a bankok régiek... But in the past and future tenses the substantive verb is required: ő katona volt ((s)he was a soldier), az ég kék volt (the sky was blue); ő katona lesz ((s)he will be a soldier), az ég kék lesz (the sky will be blue).