The Quarteira is one of a number of small rivers in the central Algarve which make up the water ecosystem known as the Querença – Silves Aquifer System.
A short distance from the confluence of the Quarteira the river passes the village of Paderne and then snakes in a large loop around a hill which is topped by the remains of the Moorish Castle of Paderne. Below the castle are the remnants of two watermills. The first is to the Acudes do Castelo[5] which is in the north-west valley below the castle and the second watermill is called Alfarrobeiro and is south of the castle. Next to this watermill stands a Bridge built by the Romans. The Roman bridge is location on the rocky peninsular bend and was of strategic importance to the Romans, as it controlled the ancient Roman road Via Lusitanorum.
