Porto is the second largest city in Portugal after Lisbon and serves as the capital of the Porto District. Situated on the Douro River estuary in northern Portugal, its urban area extends to the Atlantic Ocean coastline. The city functions as one of the Iberian Peninsula's major urban areas and is recognized globally with a Gamma + rating from the Globalization and World Cities Research Network.

Settlement dates back to the 2nd century BC as a Roman outpost known as Portus Cale, which later gave its name to Portugal. The city endured significant historical events including Muslim control, reconquest by Christian forces, and a siege during the Liberal Revolution that earned it the epithet Cidade Invicta. Its historic core was designated a UNESCO World Heritage Site in 1996.

The city features uneven terrain built on high ground overlooking the river, with medieval and modern architecture coexisting. Key landmarks include the Dom Luís I Bridge designed by Théophile Seyrig, the Clérigos Church tower by Nicolau Nasoni, and the Porto Cathedral. The historic center contains remnants of defensive walls and 15th-century houses, while the western part reaches the coast.

Porto is famous for Port wine, named after the city where cellars in Vila Nova de Gaia handled export. The local culinary identity is defined by Tripas à moda do Porto, a dish originating from naval expeditions that left locals with tripe. Residents are nicknamed Tripeiros, and the city has been honored as Best European Destination and World's Leading Seaside Metropolitan Destination.

The municipality has a population of 231,800 as of 2021, while the metropolitan area holds approximately 1.9 million people. The climate is warm-summer Mediterranean with summers averaging between 16 and 26 °C. As a busy industrial and commercial center, it offers access to beaches and serves as a starting point for the Portuguese Way of the Camino de Santiago.