A Memorandum of Understanding is to be signed today, 30 October 2008, between UNESCO and the International Astronomical Union (IAU). The IAU will be integrally involved in the process of developing UNESCO's Astronomy and World Heritage Initiative, helping to promote astronomical sites of "Outstanding Universal Value". The world-famous UNESCO World Heritage Convention is renowned for its work protecting and promoting sites that celebrate the heritage of humanity. Examples include the Pyramids of Giza in Egypt, the Mayan city of Chichen Itza in Mexico, and the Stonehenge in the United Kingdom. However, astronomical heritage is currently under-represented. All too often, neglect and mistreatment cause irreversible harm. The new Memorandum will place the Astronomy and World Heritage Initiative in a better position to reverse this trend by raising awareness of the cultural importance of astronomical sites, both ancient and modern.