You can sip port wine from any of a dozen different producers holed up in the terracotta-topped warehouses along the Gaia district's riverfront. Or, cross over the Douro River to Cais da Ribeira, the crumbling heart of the old city, and stroll down the pedestrianized, stone-tiled Rua Santa Catarina for a stint of shopping, and maybe even stop by the atmospheric Café Majestic for a melted-cheese francesinha sandwich, or pop into one of the world's oldest bookstore, Livraria Lello, and leaf through books the old-fashioned way (no Kindle!). Oh, and the views from the center-city Clérigos Tower are totally birds-eye!