Surprisingly for many people, the holiday and party island of Ibiza has a wide range of historic and natural attractions that were somewhat randomly put together in one WH site. The major sight is Alta Vila, the historic centre of Ibiza Town. It sits on a high hill similar to the Acropolis and offers great views over the sea and the island. It is surrounded by a well-preserved city wall, and features several historic buildings, including the cathedral. Unfortunately, the archaeological museum next to it has been closed for budget reasons since January 2010. A short walk away, the Punic site of Puig des Molins has been closed for similar reasons since October 2010, although you can see quite a bit through the fences. The small archaeological site of Sa Caleta, on the coast near the airport, is also included, but there is really not much to see (only a small enclosed area with a few walls and stones). The natural component is the Ses Salines Nature Reserve, which covers the southern part of Ibiza, the northern part of Formentera, and the small rocks and seas between them. Taking the ferry between the islands gives you a good overview, and I also visited the Ses Salines beach on the southern tip of Ibiza, which includes walkways through pine forests and paths along the salines. I'm not sure if I saw any of the famous Posidonia sea grass, although it is entirely possible (hard to tell from normal algae). I arrived on Ibiza by ferry from Valencia, and spent 2 days on the island. I found this to be sufficient for sightseeing purposes, but of course, Ibiza has plenty of other attractions.