A must-see while in Porto is the São Bento Railway Station. More than just a train station, this place is another architectural jewel, among the many others this city boasts. Built by the Portuguese architect José Marques da Silva in 1900, the São Bento Railway Station opened to the public sixteen years later. Its construction took place on the site that once housed a Benedictine monastery, hence the name São Bento. The architecture has a French Renaissance influence, and even though its facade is already quite impressive, its interior is what leaves visitors truly awestruck. The main hall is beautifully decorated–from the ground to the ceiling — with more than 20,000 "azulejos" (Portuguese tiles), which recount important events of the history of Portugal.

Built in 1110 in the highest point in the city, Sé do Porto, or Porto Cathedral, is a defining landmark of the city, and the most important religious building in Porto. A visit to the cathedral is well worth not only for its historical importance, but also for its remarkable mix of architectural styles that range from Romanesque to Baroque and Gothic, and lastly, for the beautiful views it offers over the city--stretching from the Old Town to the Atlantic coast.

If modern art is your scene, don't miss this museum, which hosts some of the best works by contemporary Portuguese painters and sculptors, as well as pieces from internationally-known artists such as Warhol and Pollock. The building also offers a library, a book shop, a tea house, a restaurant, and an auditorium bar. The opening hours may differ from those of the museum itself and according to the season.

The Tito Bustillo Cave is on the selected list of World Heritage and is one of the most important Palaeolithic art sites. Make sure to wear warm clothes when visiting the cave. It is also advisable to book your visit in advance.