The B3404 runs along part of the old A31 in the centre and just east of Winchester. It was created when the A31 was diverted to run as a multiplex with A272 in order to meet the A33Winchester Bypass in the mid-1970s.
The road starts at a mini-roundabout on the B3330 just east of the bridge over the River Itchen. It bends to the left to climb Magdalen Hill then bends sharply right onto Alresford Road. We continue through the city's eastern suburbs and then cross the modern replacement of the Spitfire Bridge, which crosses the M3 and A272.
Apart from a school and a handful of other buildings the road is now in open country. It continues east along the dead-straight road to end at a roundabout on the A31.