Alta Cerdanya or French Cerdanya (French Cerdagne) is an alternative name for the portion of historical Cerdanya, south of the top crest of the Pyrenees, that was ceded to the French crown by the Treaty of the Pyrenees (1659).

It is the sunniest place in France and for this reason was chosen as the place to build:

• the solar oven of Odeillo (official site) (http://www.imp.cnrs.fr/foursol/1000.shtml), used for high-temperature scientific experiments;
• the Thémis experimental solar power plant (operated by EDF from 1983 to 1986); it is now decommissionned as a power plant, but is being used as a Cerenkov telescope for the detection of Gamma rays [1] (http://www.lal.in2p3.fr/recherche/celeste/Celeste1.html)