  We present preliminary results of the first near-infrared variability study
of the Arches cluster, using adaptive optics data from NIRI/Gemini and
NACO/VLT. The goal is to discover eclipsing binaries in this young (2.5 +- 0.5
Myr), dense, massive cluster for which we will determine accurate fundamental
parameters with subsequent spectroscopy. Given that the Arches cluster contains
more than 200 Wolf-Rayet and O-type stars, it provides a rare opportunity to
determine parameters for some of the most massive stars in the Galaxy.
