Torre Espacio (now Torre Emperador Castellana)

Torre Espacio is a project of Pei Cobb Freed & Partners, with Henry N. Cobb and José Bruguera in charge of it and Reid Fenwick Asociados as associate firm. The client is Torre Espacio Castellana, of the Villar Mir group, and OHL is the contractor. The building was completed in 2008.

The tower is one of the four skyscrapers of the Cuatro Torres Business Area, built on the former Ciudad Deportiva of Real Madrid. It has belonged to the Philippine group Emperador since 2015, which gave it its present name, Torre Emperador Castellana, in autumn 2021.

The tower was conceived to evoke a living being born of the earth and growing towards the sky. The study explored how a square plan at the base could turn little by little into an almond-shaped plan at the crown, where the form arises from two intersecting quarter-circles. To make the curved surfaces of the curtain wall easier to manufacture, the building's section was divided into 44 horizontal planes; their intersections with the radial segments of each quarter circle define a vertical curve whose formula rests on the cosine, hence its name, the cosine curve. The curvature changes gradually over the full height, and this geometry yields 52 different floor plates.

The structure is concrete, from the foundation slab, 4 m thick, to the floors, walls and columns. The envelope is conceived as an "active climate wall": a double-glazed curtain wall in whose cavity the air of the rooms circulates, entering at the bottom and leaving at the top, with perforated horizontal louvres that can be raised, lowered or tilted. Six underground levels house a car park of more than 1,150 spaces.

The tower has 57 levels above ground: 43 of them are given over to offices, two more, at the top, to corporate offices, and three to shops, at the base. Two rest areas 8 m high occupy floors 18 and 33.

It is an office building, seen from the outside, from the Paseo de la Castellana and the Cuatro Torres district.