Mediaeval crusader castles in Syria and ancient irrigation systems in Oman were among 18 new cultural and natural sites added to the UN's World Heritage list this week, officials said. UNESCO, the UN environmental and cultural body, also added the Vizcaya Bridge in Spain and the mining landscapes of Cornwall and West Devon in Britain. The new sites, added at a meeting of UNESCO's World Heritage committee in Lithuania's capital Vilnius, brings the global list of cultural and natural sites to 830. The cultural body could increase the list even further at the current meeting. Officials said two more sites were still up for deliberation later, but they would not say what these sites were.