 The significance of these entrances, if any, is unknown, but they may have aligned with geographical features that no longer exist, such as other settlements.From radio-carbon dating, the Brown Caterthun appears to have been built and modified over several centuries in the latter half of the first millennium BC.Parts of the White Caterthun may have been contemporary with the Brown Caterthun, but it is believed that the main stone wall was built by the Picts or their progenitors in the first few centuries AD.