Created by Mark Davies.
Funded by the US National Endowment for the Humanities
Corpus del Espaņol has two different parts (both of which are now available with an English and a Spanish interface and help files):
(original, smaller) corpus that allows you to look at
historical changes and genre-based variation
the (newer, much larger) corpus that you can use to
look at dialectal variation (and have 100x as
much data for Modern Spanish).
Click on an [Info] link above
for more details.