One of the oldest orders of chivalry in the world, the Knights of Malta is celebrating its nine-hundreth anniversary today.

The Roman Catholic order -- which was originally set up as a military force to protect Christian pilgrims -- is now based in Rome and carries out humanitarian work all over the world, especially in the Middle East.

The anniversary is being marked in Malta with the return, by the authorities, of an old fort in the capital, Valetta, where the Knights were based until the end of the eighteenth century.