Inside pavement ants will occasionally nest in walls, in insulation, and under floors. The most likely place is in ground-level masonry walls of the foundation and especially near some heat sources in the winter. They often follow pipes which come through slabs for access to upper floors of buildings.
Outside these ants typically nest under stones, in cracks in pavement, and next to buildings. They enter buildings through cracks in the slab and walls, slab expansion joints, and the natural openings of buildings. Although not aggressive, workers can bite and sting.