In the eighties, Mateos displayed an overwhelming energy that led him to hold up to six solo exhibitions in a row. This series, called Horizontales, corresponds to 1981, a time when a change of postulates led the sculptor to place the axis of his sculptures horizontally. In this way, the monumental character of his previous work now becomes emphatically architectural.

In these pieces, the parallelism of the planes that compress the space, arranged in severe perpendicularity with the rest of the walls, favour the architectural character of this series, further enhanced by the texture of the formwork, also arranged horizontally.

Many of them have cantilevered planes supported by one or more supporting pillars, which give the work the appearance of large structures. If Mateos's early works had parallels with Brutalist architecture, at this stage the parallels are with international architecture, and especially with the work of the architect Frank Lloyd Wright, one of its greatest exponents and for whom Ángel Mateos felt special respect and admiration.

But make no mistake, Ángel Mateos is a sculptor and he never renounced the creative freedom of sculpture. His work is impregnated with monumental power and can therefore suggest great architectures. In the words of the author: "...in its relationship with architecture, traditional sculpture has been understood as an ornamental or additive element of architecture. On the contrary, these sculptures are conceived to be themselves a whole.