 The Altar of the Kings was also the work of <unk> Balbás , in Mexican Baroque or Churrigueresque style . It was begun in <unk> by Balbás in cedar , and was gilded and finished by <unk> Martínez , debuting in 1737 . It is located at the back of the Cathedral , beyond the Altar of Forgiveness and the choir . This altar is 13 @.@ 75 metres ( 45 @.@ 1 ft ) wide , 25 metres ( 82 ft ) tall and 7 @.@ 5 metres ( 25 ft ) deep . Its size and depth gave rise to the nickname la <unk> <unk> ( " the golden cave " ) . 
