While the area of present-day Celje was first settled as far back as the Iron Age between the 9th and 6th centuries BC, it first flourished after being annexed by the Roman Empire and given the status of an independent town during the 1st century AD. However, after several hundred years the town had sunk back into relative obscurity by the 6th century. This long and rich history of settlement has left Celje with quite an archaeological legacy, some of which can be viewed on an underground tour through the cellars of the Princes Palace on Trg Celjskih Knezov.