The UNESCO riverside trades views and scarcity in small, steep, often renovation-heavy stock; Foz is the seaside family premium; Boavista and the university belt are the year-round rental book. Gaia across the river is administratively separate and priced like it.
Porto froze new AL licences in its own containment zones — later and narrower than Lisbon, but the same diligence applies. The same national IMT slices and stamp duty as the capital; lower prices, lower absolute closing costs.