Jerusalem tour guides discovered what they believe is a well–preserved water tunnel from biblical times.

Running 740 feet, the long, “beautiful” tunnel was discovered during an excursion organized recently by the Etzion Field School, according to a report Friday in the Israeli daily Ma’ariv.

Yaron Rosenthal, who runs the school for the Society for the Protection of Nature in Israel, said instructors chanced upon the tunnel just east of the security barrier which separates Israel from Palestinian centers of population in the West Bank. Rosenthal estimated the structure predated 586 B.C. He said the tunnel is one of the longest tunnels in the Holy Land used to transport spring water.

He said that markings, stairs and aesthetic relief carved into the stone suggested that the tunnel belonged to a Judean king.

“We entered a 15-foot shaft through a very narrow entrance and headed eastward underground,” Rosenthal recalled. “We were amazed at the beauty of the structure we were in, whose corridor is built from huge slabs of more than a cubic yard. At the end of this construction, a simpler path begins and a neat staircase leads to that part.”

The tunnel’s ceiling varies between five and nine feet and it is two to three feet wide, he said. The tunnel is within Jerusalem’s municipal boundaries, according to Ma’ariv.

The Israel Antiquities Authority conducted preliminary checks in the region three years ago but decided not to excavate, according to Ma’ariv.