The B663 is a largely rural B-road in the east Midlands.
It starts at A14J15, the rather unexpected crossroads on the edge of Bythorn which is the road's first at-grade junction since leaving the M1. The B663 winds south from here via Keyston before running along a dead-straight road for about a mile. This bends sharply right and enters Raunds.
At the near end of the High Street the road splits. The right fork heads west to a roundabout, then north to join the A45; this section was originally the B666. The mainline continues ahead to a mini-roundabout. Originally the road continued ahead via Stanwick to end on the A6 at Higham Ferrers; this section became part of the A605 early on and now is partly A45 and partly unclassified. In 1935 the road was extended to the left and so now continues south to end at a triangular junction on the B645 in Chelveston.