MOSCOW, March 31. /TASS/. A secret chamber used for eavesdropping on enemies in the 16th century was discovered in downtown Moscow, which is undergoing a major gentrification project, City Hall said on its website on Friday.

"Archeologists found a small vaulted chamber in a trench dug near the St. John Church (some 700 meters away from the Kremlin)," the capital’s chief archeologist, Leonid Kondrashev, was quoted as saying.

He said this chamber had helped Moscow’s defenders to snoop on enemies on the other side of the city’s wall.

In all, more than 150 artifacts dating back to the 16th-19th centuries were unearthed during the renovation. Among them are coins, ceramics, utensils, bullets, buttons, an arrow and a cannon ball.

The renovation of Moscow’s streets began last year. This spring and summer, 87 downtown streets are slated for gentrification.