The UN's cultural watchdog has called on Russia to stop a 400m (1,312 ft) skyscraper being built in historic St Petersburg's city centre.  Unesco said the planned $2.4bn (£1.5bn) Okhta business centre tower would "damage the image of Russia".  Local authorities have approved construction of the building, which will house offices of the state-controlled energy giant Gazprom.  St Petersburg's city center is listed by Unesco as a world heritage site...more.