I'm trying to find the birth certificate of my grandfather. He was born in 1880 and was born in Madrid while his parents were on vacation from Cadiz.  I'm not sure weather I should be looking in Madrid or Cadiz, but I did start my inquiry in Madrid.  I sent a request for his birth certificate to the archivo/registery in Madrid and they responded telling me that they did not have the birth certificates for people born betwen 1870-1890. 

 Any help any one can give me on where to look next would be great!