elements Scholarly debate has taken place over the definition of a bastide. They are now generally described as any town planned and built as a unit, by one founder. Most bastides were developed with a grid layout of intersecting streets, with wide thoroughfares that divide the town plan into insulae, or blocks, through which a narrow lane often runs. They included a central market square surrounded by arcades (couverts) through which the axes of thoroughfares passed, with a covered weighing and measuring area. The market square often provided the module into which the bastide is subdivided. The Roman model, the castrum with its grid plan and central forum, was inescapable in a region since Roman planning precedents survived in medieval cities such as Béziers, Narbonne, Toulouse, Orange and Arles. The region of the bastides had been one of the last outposts of Late Antiquity in the West. Central square The main feature of all bastides is a central, open place, or square. It was used for markets, but also used for political and social gatherings. A typical square, (which was probably a model for other bastides), can be found in Montauban. Generally, there is just one square. Saint-Lys and Albias are different because they have two squares, one for the market and one square for the church. The square is also used to divide the city into quarters. Generally, it lies outside the main street (the axis) which carried the traffic. There are three possible layouts: Completely closed: The square does not touch any street. These are very rare; there is one example at Tournay with a size of 70 metres (230 ft) by 72 m (236 ft)). Single-axis: The single-axis design of the bastide makes all roads run in one direction and are parallel. Here and there, there are alleys cut between the roads. The square is placed between two roads. These squares are usually 50 m (164 ft) to 55 m (180 ft) on each side. Grid-layout; usually based on the square in Montauban. Generally the flattest place in the bastide was used for the square. Church The church was almost never on the central square but usually at an angle, facing the square diagonally. One of the rare exceptions is Villefranche-de-Rouergue but this one was built two centuries after the square. Houses There were clear rules how houses could be built inside the bastide. The front of