In this series the sculptor investigates the compositional possibilities based on the plane, and in it, the premises are a concern for balance and proportions.

With a constructivist approach, close to Dutch neoplasticism, Mateos imprints a marked monumental and architectural character. In them, the artist conceives a more open and dynamic space, in which he includes the surrounding space around the work. Mateos invites the viewer to move between the planes and imagine an entrance portico. We can say that there is an intention to intervene in the landscape.

In this series, the PÓRTICO A SALAMANCA is one of the artist's best-loved works and one in which the balance of the composition is at its best. In it, the two vertical walls that act as jambs of the door are articulated together in a knot of perpendicular planes that break in the opposite direction. To its right, a higher, free-standing vertical wall acts as a counterpoint and provides the balance that the author sought for the whole.

This Portico was conceived as a gateway to the city, and it would almost have been completed had it not been for the sculptor's intransigence in considering a scale in accordance with the ever-reduced official budgets. If we look at it from a low viewpoint, we can intuit another scale, the one Mateos imagined. Never before have his sculptures been so susceptible to being "models of themselves".

Another work in this series, the sixth portico, was made in 2002 by the sculptor for Doñinos. Made of large sheet iron and erected on the side of the road, just 100 metres from the museum, it was donated in gratitude to the municipality that hosted his museum.