<prompt> Translate the following text to EnglishWakati mmoja ilikuwa mahali pa kuwinda kwa watu wa kifalme na wageni wao, lakini mwaka 1973 mji wa Chitwan ukawa mbuga ya kitaifa na UNESCO ikauita eneo la urithi wa dunia.  <response>: Once the private hunting ground of royalty and their guests, Chitwan became a national park in 1973 and has been designated by Unesco as a World Heritage Site. 