Two communication towers have been built in the courtyards of the Cathedral open to the cornerstone of Santa Maria, on its north façade, in order to complete the route for the tour of the Cathedral, on the one hand providing access to the space under the portico roof—above its vaults—and from here to the inside of the tower, and on the other communicating the lower level of the chevet crypt with the floor level of the Cathedral.
The first of these towers, the portico one, is located in the western courtyard and houses a lift fully accessible from three stops, the lower one at the level of the courtyards of the cornerstone, the second one at the level of the main floor of the Cathedral, and the third at the level of the future exhibition hall above the vaults of the portico. It is made of sandstone in contorted shapes following a geometric pattern that simulates the conversion of a square into a circle via a pentagon, hexagon, heptagon and octagon.
The second tower, in the eastern courtyard, next to the transept, connects the two levels of the Cathedral, the semi-basement that can be visited and the ground floor, the former at the height of the courtyard of the cornerstone and the latter at the level of the Plaza de Santa María, on the southern side of the Cathedral, and it also houses an accessible lift. It is cylindrical and is also built in sandstone, though it additionally has an external spiral staircase made of limestone and a small vaulted platform that gives access to the upper level and protects the lower level from the elements.
