JERUSALEM — A new archaeological discovery may require a revision of the ancient history books — and of the Bible.

Recent archaeological digs have provided evidence that Jerusalem was a big and fortified city already in 1,800 BCE, about 800 years before King David conquered the city from the Jebusites. The new findings contradict the theory that prior to David's raid on Jebus, Jerusalem was a poor and small village.

Gideon Avni, a Jerusalem archaeologist, said earlier this month that the entire concept on the City of David, the core of Jerusalem's Old City, would now have to be changed.

The digs at which the discovery was made took place near the Gichon spring, Jerusalem's main water source.

Findings there show that the sophisticated water system heretofore attributed to the conquering Israelites pre-dated them by eight centuries and was even more sophisticated than imagined.

At a recent press tour of the site, archeologists of the Israel Antiquities Authority said the famed Warren's Shaft was only a natural fissure in the rock that had nothing to do with the water system.

The 50-foot-high shaft, accessed from a tunnel, was previously believed to be the way the ancients accessed the waters of the Gichon from within the walls without exposing themselves to forces besieging the city.

Excavations in the past few months have exposed a tunnel that skirted the shaft and brought residents of the city directly down to a pool near the spring.

Contrary to previous belief, the spring itself was heavily fortified and not outside the city's defenses.

Dr. Ronny Reich, who directed the excavations along with Eli Shuikrun, said the entire system was built as a single complex by Canaanites in the Middle Bronze Period, around 1,800 BCE.

"We have to rethink all our concepts about the City of David that were formed over the last century," said Reich.

Warren's Shaft was discovered by British explorer Charles Warren in 1867 and was believed to have been the linchpin of the ancient water system.

Ceramics found in the current investigations tie the system firmly to the Canaanites, 800 years before David's conquest, said Reich.

The excavations also uncovered on the lower eastern slope a fortified wall from the Middle Bronze Period in an area believed to have been outside the city's defenses.

This could mean that the Canaanite city was almost twice as large as previously believed, said Avni.