A 20-year-old man was assaulted in Cottingham Road, Corby, close to the new building development.
The incident happened at about 4pm on Monday, 8 December.
The victim was walking with a bicycle when a man got out of a green Volkswagen and pushed him against a fence before punching him. This caused bruising, a broken tooth and a cut lip which needed stitches.
The incident was witnessed by a woman in a red car who stopped at the scene. Police are appealing for her to come forward.
Witnesses, or anyone with information, are asked to call Northamptonshire Police on 101. Alternatively, they can call Crimestoppers on 0800 555111.