In the film, which is a part of the NOVA series Secrets of Lost Empires, a team of timber framers and other specialists design, build, and fire a pair of trebuchets, a devastating engine of war popular in the Middle Ages.

The film, which is a part of the NOVA series Secrets of Lost Empires, documents a 1999 effort by a NOVA-assembled crew of scholars and timber framers to design and build a Chinese bridge known only from an ancient painting.

In "Tattooed Doctor," the first hour of NOVA's "Survivor M.D." series, emergency-room physician Dr. Tom Tarter eloquently describes some of the challenges and rewards of emergency medicine.

In 1987 NOVA embarked with seven brilliant, natural-born survivors on the longest-running boot camp in higher education: the nearly decade-long process of training to be a fully qualified doctor. Now all but one of them (who switched careers) are out in the world in high-powered medical careers, trying to balance the demands of work, families, and personal lives, as NOVA reports on Survivor MD, which airs in three one-hour segments.

In 1987 NOVA embarked with seven brilliant, natural-born survivors on the longest-running boot camp in higher education: the nearly decade-long process of training to be a fully qualified doctor. Now all but one of them (who switched careers) are out in the world in high-powered medical careers, trying to balance the demands of work, families, and personal lives, as NOVA reports on Survivor MD, which airs in three one-hour segments.

Relive the engineering challenges that two bicycle makers overcame to become the first in flight.