The Institute main building is the Rockefeller building, is an historical landmark in Spanish Science. It was inaugurated in 1932, and was the first (only?) advanced physics and chemistry laboratory at the time. Enrique Moles, Miguel Catalan (of optical multiplet fame) and Blas Cabrera all worked here in its heyday.

Your first need to reach the front of the Rockefeller building. Once you get there, you are nearly at our lab:

 Just as you are facing the entrance, move to your left, and keep goind around the main building

 A bit farther, at the corner, you will end up in front of our lab (there are only two small buildings in that area, ourselves and the Magnetic Resonance building, ours is the one on the left):