The Santa María Cathedral is by far the most interesting monument in Burgos. This classical Gothic structure features a three-storey façade, many chapels and a massive 16th century crossing tower topped with eight ornate spires. The monumental west wall has two bell towers with open latticework spires with saw-like profiles. On the north side is the Escalada Dorada or Golden Stairway dating from the Renaissance period. The Sarmental Door (on the right transept alongside the cloister) is well conserved and the style of the sculpture in the tympanum is very realistic. The north transept portal has statues of the twelve apostles while the south portal features the evangelists at their writing desks. A long staircase connects the sacristy and cloister. The cathedral contains many works of art, tombs, including that of "El Cid", altarpieces (the rear part of an altar, usually carved or painted) and a beautiful choir chair. The richly decorated Chapel of the Condestable is octagonal in shape and has eight small spires. The tombs of "El Cid Campeador", Burgos’ most famous son, and Doña Jimena, are situated beneath the cupola. The grilles between the transept and choir are magnificently worked and gilded. The walnut chairs of the choir stalls are all different and inlaid with boxwood.