Mysterious stone carvings made thousands of years ago and uncovered recently in an excavation underneath Jerusalem have archaeologists stumped. Israeli diggers who uncovered a complex of rooms carved into the bedrock in the oldest section of the city recently found the markings - three "V" shapes cut next to each other into the limestone floor of one of the rooms, about 5 cm deep and 50 cm long. There were no finds to offer any clues to the identity of who made them or for what purpose. The archaeologists in charge of the dig know so little that they have been unable even to posit a theory, said one of the two directors of the dig. "The markings are very strange, and very intriguing. I've never seen anything like them," he said. The shapes were found in a dig known as the City of David, a politically sensitive excavation conducted by Israeli government archaeologists and funded by a nationalist Jewish group under the Palestinian neighbourhood of Silwan in east Jerusalem. The rooms were unearthed as part of the excavation of fortifications around the ancient city's only natural water source, the Gihon spring. It is possible, the dig's archaeologists say, that when the markings were made at least 2,800 years ago, the shapes might have accommodated some kind of wooden structure that stood inside them, or they might have served some other purpose on their own. They might have had a ritual function or one that was entirely mundane. Archaeologists faced with a curious artifact can usually at least venture a guess about its nature. In this case, no one, including outside experts and the dig's co-director, archaeologists with decades of experience between them, has any idea. There appears to be at least one other ancient marking of the same type at the site. A century-old map of an expedition led by the British explorer Montague Parker, who searched for the lost treasures of the Jewish Temple in Jerusalem between 1909 and 1911, includes the shape of a "V" drawn in an underground channel not far away. Modern archaeologists haven't excavated that area yet. Ceramic shards found in the rooms indicate they were last used around 800 B.C., with Jerusalem under the rule of Judean kings, the dig's archaeologists say. At around that time, the rooms appear to have been filled with rubble to support the construction of a defensive wall.