The way to travel from the airport to the center is by bus of Empresa Freire, the time list must be inquired there, and the final stop is at the bus terminal or in Doctor Teixeiro street. Here the best option is to walk until Plaza de Galicia and then pick up the bus no 5, or 15 and get off at San Roque stop.
From the bus station the bus no 2, and 5 until San Roque stop.
From the railway station walk to Parlamento de Galicia stop and then the line 6 or C6 until Compañía de María stop and then several lines no 1,2,4,5,13,15 until San Roque stop.
When you arrive at San Roque Stop, you must follow the way to the Cathedral and go straith on and turn right on the 2nd street and then turn on the left (it is about 2 minutes walking).