The Diamond is the main square in Donegal Town. It forms the town centre with an extensive pedestrian area with seating and trees. It includes a prominent 'obelisk' celebrating 'the Four Masters', four Gaelic historians led by Brother Mícheál Ó Cléirigh who wrote The Annals of the Four Masters in the 1630s. The Plantation of Ulster and the establishment of 'plantation towns' often included a meeting area or market place (often with a 'mercat cross') in the town centre.