While technically its own municipality, Vila Nova de Gaia ('Gaia') sits just across the Douro from Porto and is woven into the city's fabric both by a series of stunning bridges as well as its shared history of port-wine making. Since the mid-18th century, port-wine bottlers and exporters have been obliged to maintain their 'lodges' - basically dressed-up warehouses - here.
Today some 60 of them clamber up the steep riverbank, and at night the entire scene turns into Portugal's version of Las Vegas, with huge neon signs clamouring for the attention of winos and oenophiles alike. This enclave of historic terracotta-topped warehouses is now Porto's best-known attraction, despite not actually being in the city at all. Vila Nova de Gaia is a wholly separate municipality, and - beyond the riverbank - goes about its own business in kind of parallel universe. Most visitors are not interested in exploring further than the stunning waterside promenade - lined with beautiful barcos rabelos and offering spectacular views back to Porto - and the maze of warehouses that dominate the hillside above it. About two-dozen lodges are open for tours and tastings on weekdays and Saturday. In high season (June to September) the larger ones run visitors through like clockwork and you'll wait no more than 15 minutes to join a tour. At other times they can accommodate you more or less on the spot.