Complex sentence: The highest point is the Roque de los Muchachos on the northern wall, at 2423 m altitude, today the site of the Roque de los Muchachos Observatory.
Split into simpler sentences: The highest point is the Roque de los Muchachos on the northern wall, at 2423 m altitude. The summit is also the site of the Roque de los Muchachos Observatory.