New Delhi, March 14: The National Remote Sensing Centre of ISRO has signed an agreement with the Archaeological Survey of India (ASI) for preparing satellite-based maps to help check unauthorised construction around over 3,000 protected monuments, the government said on Monday. Culture and Tourism Minister Mahesh Sharma said this on Monday while replying to a question in the Lok Sabha. The maps will indicate prohibited and regulated areas around protected monuments for the information of the public. "The ISRO (Indian Space Research Organisation) has a repository of photographs that are taken routinely through satellite. Those photographs will be used for developing a surveillance system for the centrally protected monuments," Sharma said.