Cl. Alain Lonchampt © CNMHS, Paris.   
North-eastern section of the
Roman wall. Remains of the
Late Empire wall set off from
the curtain wall built at the end
of the XIIIth Century between the
Moulin Tower (in the background)
and the Trésau Tower.
Reconstitution : Ecole d'architecture de Charenton
 he IIIrd and IVth Century A.D. wall runs more than 1,000 m. round the hill. Its lines correspond to the medieval inner ramparts with the exception of two sections: on the south-west corner and on the section made up of the Trésau Tower and the Moulin and Connétable Towers. The levelled masonry is still visible behind them.
The construction of the curtain walls and towers used small bond with carefully cut blocks of sandstone and layers of brick. Of the thirty or so towers that initially defended the edifice 22 remain today, some in ruins and others with entire elevations preserved. This is particularly true of the Moulin, Connétable, Vieulas and Marquière Towers which dominate the North facade.
They are built in a horseshoe shape – semi-circular on the outward face and flat on the inner elevation facing the walled city. Built on a square base, the first two levels are constructed in solid masonry to reinforce the whole structure. There are windows with roman arches but these are only on the top storeys. Two posterns whose lintels are reinforced with brick and sandstone slabs survive in the wall : one against the Pinte Tower and the other facing the Moulin d'Avar tower.


 Late Empire Wall
 The St-Sernin Tower
 The Moulin, Connétable,
 Vieulas, and
 Marquière Towers
 The Avar Postern
  The Moulin, Connétable, Vieulas and Marquière Towers on the North facade.
  Cl. Alain Lonchampt © CNMHS, Paris.