The city of Porto is known as the city of "Invicta". It's the city that gave its name to Portugal very early in 200 BC, and was later to become the capital of Portucalense. It is still a city known worldwide for its wine, bridges, ancient and contemporary architecture,and  its historical center is listed as  a World Heritage site by UNESCO. With its beautiful monuments and historic buildings, such as the imposing cathedral and the Tower of Clerics, Porto is the second largest city of Portugal, offering a superb harmonious synthesis of old and new attractions. On the opposite bank of the river, Vila Nova de Gaia has superb views of the world-famous Port wine cellars, and is the main production center of Port wine. You can see where the wine is blended and aged, plus taste different varieties. Alternatively, you can opt for a cruise on the Douro.