A few years ago the Ayuntamiento of Santiago del Teide published a great book to celebrate it's 500th Anniversary.
Quite a large book, print in Spanish, but wonderful pictures showing the development of the area in terms of, social tourism, agriculture, etc. A must for all lovers of the area. I got my copy, and several more for friends, from the Tourist Office at Playa de la Arena, for about 10 Euros. Worth making enquiries to see if there are any more available because it's a great history of the area a lot of us love. One picture from the mid 1960's shows the road through Playa de la Arena as no more than a dirt track, evidence of how quickly the area has developed.