Complex sentence: He signed the message, "Phil was here," picked up a chair, hurled it and then himself through a window on the fifteenth floor of the Earth, Atmospheric & Planetary Sciences building, commonly known as the Green Building.
Split into simpler sentences: He signed the message, "Phil was here," picked up a chair and hurled through a window. He jumped out the window on the fifteenth floor of the Earth, Atmospheric & Planetary Sciences building, commonly known as the Green Building.