The B3404 runs along part of the old A31 in the centre and just east of Winchester.
The road was renumbered from a spur of the A31 in 1972. That road had been diverted to run as a multiplex with A272 in order to meet the A33Winchester Bypass when the Chandler's Ford Bypass section opened in 1968, but the old road was not immediately renumbered.
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.