Most of the major sites in Porto are within walking distance of each other or accessible via public transportation. The city tram is a great way to explore the historic center and costs €3 per trip, or €6 for a day pass. Alternatively, Uber and taxis are widely available and affordable.
If you have more time, consider visiting the Serralves Museum of Contemporary Art or taking a day trip to nearby Braga or Guimaraes. If you have less time, consider skipping the Palacio da Bolsa or Livraria Lello to allow for more time at other sites.
Oporto Airport (OPO) is located approximately 11km from the city center of Porto. It is a busy international airport with direct flights to many major cities in Europe and beyond.