Porto (Oporto) gave us the name of Portugal and port wine.

The Lello Bookshop (1906) is at the 'gothick' end of gothic, and must be one of the most ornate bookshops in the world.
Porto Cathedral is a brutal, battered, ocean-going church, grounded upon a crag; the sort of thing you might expect to find at Plymouth. Only the cloister is enlivened by the azulejo tiles common in Portugal.
São Francisco is outwardly gothic, but conceals a baroque interior encrusted with gold.