The A520 is a link in western Lisburn, serving new development.
The road starts at traffic lights on the A519 Prince William Road and heads west along Knockmore Road. Side roads serve retail and housing but little of this is visible from the A520 as the road is lined with trees. The road soon starts bending round to the left and is soon heading southwards. It goes over the Belfast to Dublin railway line and then descends to traffic lights on the A3, where the road ends.