Iranian archeologists hope a newly-discovered tunnel in Bonab, northwest of Iran, is likely to lead them to the legendary city of Shiz, dating back to 7,000 years.

Shiz is believed to have been one of the most prosperous cities in ancient Persia and historical documents indicate it housed over ten thousands people during its booming days. Experts cannot, however, agree on the geographical location of the city, which is believed to have been older than Susa, southwest of Iran.

Different parts of the Western and Eastern Azerbaijan provinces have been so far excavated but with no avail. But right now the discovery of an underground tunnel in Bonab has raised some hopes among the experts.

“The tunnel was, indeed, discovered a few years ago in an area of Bonab named Pasigan, though it was initially unattractive for the archeologists. New studies have indicated the tunnel could possibly lead us to the long-lost city of Shiz, however,” said Mohammad Gharbi, an expert with Iranian Cultural Heritage Organization in Bonab.

The tunnel is 12 km long and 0.8 m high and clearly reveals the impact of sledge hammers used to burrow it. Experts speculate it might have served as a clandestine escape route for the aristocrat residents of Shiz.