Muscovy pauses for a moment before they enter, observing the house and the surroundings so he'll find it again when he returns alone at another time. It's helpful that Bianca's name is on the door, but also makes him think.

He'll peer around as they enter.

"It is big."

Big-ish, but two floors and at least six rooms if the number of doors is anything to go by.... that's a lot.