Roman Luca was founded as a Latin colony in 180 BC and became a municipium in 89 BC. The grid plan of the Roman nucleus , centred on the cardo and decumanus that crossed at the forum (near the present Piazza S Michele), is still discernible in the south-western part of the city. Heavy walls enclosed the city on four sides, wider on the north to include the Roman theatre (near S Agostino). The amphitheatre (Anfiteatro Romano), also to the north, remained outside the walls; its elliptical form is preserved in the Piazza dell'Anfiteatro.