In 1983, a stone weighing 200 grams fell from the vault. In 1985, a 800 kilograms of stones in danger of falling were removed. This operation revealed the presence of continuous cracks, which indicate the movement of the monument. In 1987, a survey was made to determine the measures to be taken in restoring the monument. In 1988-89, two programs of restoration work were carried out: A) Façades: Cleaning, in addition to: a) Replacement of damaged stone blocks and sculptures; b) Mineralization of blocks which suffered surface damage only; c) Waterproofing the whole monument. B) Masonry: a) Injection consolidants and mineralisants into the joints of the foundations; b) Placing three networks of tension cables above the vaults; c) Waterproofing the ground-level esplanade.