The tunnel that served as the city's only means of communication with the outside world is to be made into a museum. You have reached a premium content area of TOL. To read this entire article please login if you are already a TOL subscriber. Not a subscriber? Subscribe today for access to: Full access to the website, including premium articles videos, country reports and searchable archives (containing over 25,000 articles). You can subscribe here to gain access to the entire website.