To move around in Porto using public transportation, you will first need to understand how the system works. The city and the outskirts are divided between zones in which some titles of the public transport grid are valid and others are not. The city center is located within PRT1 (yellow area), while the PRT2 and the PRT3 also are within the city limits. Universidade Católica Portuguesa is located in Zone PRT2.

This classification is quite recent so you need to make sure you are buying the right title for the intended area. As you can see in the following map of the Subway grid, there are no direct lines to Universidade Católica (which is in C2, now PTR2). You can use Line E (Purple Line) to get from the Airport to the city center directly (or viceversa).
You may also wish to use this Line to get to a bus stop where there are connecting routes to Universidade Católica (as is the case of the Blue Line of 200, 204 or 203).
To check for bus stops and schedule as well as any changes to the service, please use the following link https://www.stcp.pt/pt/linha-azul/
Buses There are several buses that can get you directly to Campus:
The bus fare is 1.20 Euros (if you buy the ticket in advance) or 1.85 Euros (if you buy it at the bus). A daily ticket is also available for 7 Euros and can be used for an unlimited number of bus trips, during the same day.
Subway – The subway is modern and quite convenient for many destinations, except to go to campus Foz. There is a direct line between the airport and the city centre. The subway stop at the airport is right across the arrivals gate.
For further information, please visit: www.metrodoporto.pt and www.itinerarium.pt
Taxi – Taxis are relatively cheap in Porto. You can call a taxi through the following phone numbers:
+351 22 507 39 00 – (Rádio Táxis), +351 22 507 64 00 (Táxis Invicta)