One would hardly come to Porto (or Oporto depending upon which map you use) without visiting their world renowned port houses. All stretched along the hillside on the south bank of the Duoro River in Porto there are many to choose from. We picked Sandeman and Taylor Fladgate. Port can be bottle aged (the vintage fortified wines we already knew well) or barrel aged (tawny ports meant to drink younger than the bottle aged ones.) A new discovery was white port which we drank locally as an aperitif with seltzer water and a citrus twist.