This aqueduct sits in a tangle of dusty pathways and glades 4km north of central Tarragona, just off the AP7 freeway (near where it intersects with the N240). It is a fine stretch of two-tiered aqueduct (217m long and 27m high), along which you can totter to the other side. Bus 5 to Sant Salvador from Plaça Imperial de Tàrraco, running every 10 to 20 minutes, will take you close, and you can walk back to the city along the river (about 90 minutes).
Driving offers more flexibility; park in one of the lay-bys marked on either side of the AP7, just outside the freeway toll gates.