The Chapel of Castille, Leon and Portugal underwent major restoration interventions in 2011. The restoration project consisted of the restoration of the dome and wall carvings. The dome and walls of the chapel had suffered extensive deterioration due to infiltration of rain water, rising damp and candle soot deposits. Re-gilding was carried on the areas such as the dome that had lost the original gilt layer. This was carried out using 24 carat gold leaf adopting the mordant technique or water gilding technique accordingly to the process originally used in the 17th century. The flat surfaces forming the background of the carved walls were retouched with water-based pigments.