How do I verify a Portuguese plot is actually buildable before signing?

Three documents, in this order: the land registry classification (rústico vs urbano), the municipal PDM rules for that exact parcel, and any current, valid licensing decisions — all checked at the câmara, none taken from the listing or the seller. Cost: a few hundred euros and about a week. Every euro of 'discount' on an unverified plot is priced risk, not opportunity. Verify before the promise contract; afterwards you are negotiating from inside the trap.