Porto is a city located on the Douro Estuary in Portugal. It is the second largest city in the country and is known for its historical importance, vibrant culture, and stunning architecture. The city is also known for its port wine production, which has been a major industry since the 18th century. Porto is a popular tourist destination, with many attractions such as the Clerigos Tower, the São Bento Railway Station, and the Palácio da Bolsa.