(the ancient Aernia), a town of Naples, province of Molise, on a spur of the Apennines, 23 miles W. of Campobasso. It is one of the most ancient towns of the kingdom, having been in the Roman times a stronghold of the Samnites. The massive remains of its polygonal walls still exist as the foundation of the modern ones in nearly their entire circuit. An aqueduct hewn in the solid rock, and numerous remains of the ancient town, are still to be seen. It is the see of a bishop, and the chief town of a district. The cathedral and a great part of the town were destroyed by an earthquake in 1805. Pop., about 8000.