Between Twelve and Midous the growth made itself, on the one hand according to the site of confluence that was used in totality, the other, in relation with the axes of circulation of which the main was the one that came from Roquefort, crossed the Midou then.
If the limits of the 1st castelnau are as us evoked them previously, the road of Roquefort penetrated there either in the axis of the Rue Pujolin either, after having bordered the surrounding wall by the north, to height of the western portal of the Madeleine's church, to reach the castle then by the street of the church and the one of the Castle-old.
In these conditions, the development of the agglomeration was not able to make itself that of enveloping manner around the castelnau, of which the primitive ditches and the paths that edged them outside became the main streets of the new city: Big-street and street of Gourgues.
But, when the whole zone of confluence was occupied, if the new agglomeration won by it in symmetry, the primitive castelnau was rejected then in the southwesterly angle. The fragmentation of the beginning of the XIXème century translates the stages of this evolution again: to the parcels irregular enough of the former castelnau modeled according to established streets to go against the castle and the church, oppose those disposed along the Big-street and the Rue Maubec, cut in the shape of stretched out parallelograms.
The Rue Maubec, so besides that the Rue Pujolin - to the southeasterly angle - join to their extremities the Big-street drawing a coarse spindle thus. On the other hand, the Rue Maubec and the Rue de Gourgues separated little of the Twelve by parcels deep that come to stumble to the rampart whose tracing follows the course of the river.
However, he is that 2 of the most former houses of Mont de Marsan that one cannot date with precision make a mistake of reference, but that could really carry up to the XIIIème century, give on the Rue Maubec and on the north rampart: they testify thus of the fast extension of the castelnau.
If the tracing of the surrounding wall then the defensive wall that edged the agglomeration of the side of the Midou was, as in border of the Twelve, determined by the rupture of slope that underlines the course of these 2 rivers, it is more delicate to determine in what places was located the oriental limit of the city successively and what were the sites of the door of Roquefort, attested for the 1st times in 1270.
When one considers the plan of the beginning of the XIXème century, one notes that the city is crossed of part in part by a Big-street that confounds itself with the axis of the interfluve and clear, to the west, on the bridge of Midsummer's Day of August.It is likely, on the other hand, that the door of Roquefort was always established to the extremity of this street; it remains to know in what place.
It is here that it agrees to evoke a certain number of buildings undoubtedly medieval that occupies the southeasterly angle of the city: it is about the Romanesque castle, of the dungeon of the Cataye and a chapel.
The most oriental and most imposing as is the dungeon of the Cataye that one can make go back up, to the earliest, in the beginning of the XIIIème century. So, as we suppose it, it was raised to protect the city of the side of the west, it would mark its extension therefore toward 1200-1250; there would have been therefore, from this moment, a stop in the development of the agglomeration montoise, in this sector of the less.
