ALEPPO, Syria, (AFP) - The majestic citadel atop Syria's ancient city of Aleppo, the Masyaf fortress and the castle of Arab conqueror Saladdin have all been given a new lease on life as part of a project by the Aga Khan to promote Islamic sites. "We don't do enough to illustrate to the people of our world the greatness of Islamic civilisations," the 71-year-old billionaire spiritual leader of the world's 15 million Ismailis told AFP in an interview. The Aga Khan said at a recent ceremony capping work in Aleppo that his goal is to educate the world on the wealth of Muslim culture. "Because they don't know our history, they don't know our literature, they don't know our philosophy, they don't know the physical environment in which our countries have lived, they view the Ummah (the Muslim nation) in terminology which is completely wrong." The 13th century citadel is in the heart of Aleppo - one of the world's oldest inhabited cities at the crossroads of ancient trade routes - and is a World Heritage Site along with Saladdin's castle. Battered by a long history of bombardments, pillage and earthquakes, the citadel's surrounding walls and some of its 19 towers were strengthened while two mosques, a hammam or bathhouse and a palace were also restored. For five years dozens of workers restored the minaret of a mosque, baths and the imposing palace within the castle of Saladdin, originally built by the Crusaders on a windswept mountain ridge. The Masyaf fortress is a mediaeval eagles' nest. General conservation work was carried at the rugged site, and part of an outer wall was rebuilt. The Aga Khan Trust for Culture carried out the work in close collaboration with Syria's antiquities department, and also revamped the landscape around all three sites to make it more tourist-friendly. "My interest in working in Syria is to take the various lead countries of the Ummah and say, let's start, let's move together, let's revive our cultures so that modernity is not only seen in the terminology of the West, but in the intelligent use of our past," the Aga Khan said. Fuelled by his enormous wealth the Aga Khan - who ranks 11 on the Forbes list of the world's wealthiest royals with a fortune estimated at one billion dollars - has since 1967 also led an apolitical, secular foundation. "In the Judaeo-Christian world, charity is a notion which evokes generosity with nothing in return," the Aga Khan told AFP on the sidelines of his visit to Syria. "In Islam, the 'best of charities', but not the only one, is to help the poor be self-sufficient," he said. "I was born with Islamic ethics, in a Muslim family. There is nothing wrong with being well off as long as money has a social and ethical value and is not the object of one's own greed. "That is why I wanted to set up institutions that can manage everyday problems based on Islamic values. Restoring Islamic sites in Syria was also central to his goal of building bridges between religions and cultures. "Syria wants to be a secular state where all religions co-exist, even if the majority of the Syrian people are Sunni" Muslim, the Aga Khan said.