The "Pabellon de Cristal" has 20,200 m2 of exhibition space, divided in three floors connected by elevators and escalators. The original project was written in july 1964 by Francisco Asís Cabrero, with the works starting on august 5, 1964 and finishing on may 1, 1965. The integral refurbishment of the glass pavilion is carried out to correct the material and programmatic obsolescence. The works are carried out in 5 independent phases of four months during the summer period so as not to interrupt the annual operation of the space. The glass pavilion is a building cataloged as a BIC, "good of cultural interest", so the works have been sensitive to the heritage requirements of the Community of Madrid and town hall. The refurbishment focused on recovering the original state of the project in terms of the main spaces, creating new service and circulation areas adapted to the functional needs of today, eliminating architectural barriers and adding elevators for a better flow. In addition to the restoration and comprehensive renovation work inside the building, two large outdoor actions were necessary: the construction of an underground floor connected to the building by means of an underground gallery and the addition of very light metal staircase towers connected with walkways to the building as new evacuation routes.