Let’s see what I can remember.
We have παλαιοπωλείο, which can be a junk shop (παλιατζίδικο, colloquially) but also an antique shop.
We use the French word αντικερί for antique shop. They often advertise themselves using the word αντίκες.
An αρχαιοπωλείο deals in ancient artefacts in the hands of private collectors or copies of ancient artefacts.
Architectural antiques are αρχιτεκτονικές αντίκες. We don’t seem to have shops using that name. They would still call themselves αντικερί (perhaps, αντικερί αρχιτεκτονημάτων) or, at best, simply αρχιτεκτονικές αντίκες.