David Walentas is the co-founder, with the late Jeff Byers, of Two Trees Management, a real estate development firm credited with transforming Dumbo from a derelict industrial area into a high-end residential enclave. His son, Jed Walentas, is the chief executive of the firm and has assumed daily operating responsibility. Walentas began piecing together his Dumbo properties in 1978 with the purchase of the Clock Tower Building for $6 a square foot, or $1.5 million for the 250,000-square-foot structure. At the time, it housed a tape business whose trucks had a hard time navigating Dumbo's narrow, stone-covered streets. He grew up in Rochester, N.Y., went to the University of Virginia on a Navy ROTC scholarship, and graduated with a degree in mechanical engineering. He also attended business school at Virginia, and graduated in 1964.