Alghero's Fertilia Airport (AHO) is 12 km north of town and receives direct flights from many European cities, including London (Ryanair), various German cities, and several Italian airports. A bus service (Volabus) connects the airport to the city centre; taxis are also available.
From Sassari, regular trains take about 35 minutes and arrive at Alghero station, which is on the outskirts of town — a shuttle bus runs to the centre. Buses from Sassari also run more frequently and drop you at Via Catalogna near the old town, which is more convenient.
From Cagliari, the drive north via the SS131 takes about two hours.