Famadihana (literally, the 'turning of the bones') is the name given to the traditional exhumations of dead ancestors by the Betsileo and Merina people. Famadihana are joyous and intense occasions, which occur in each family roughly every seven years. Amid feasting, drinking, music and dancing, the bodies of the dead are disinterred from the family tomb, wrapped in bamboo mats, and carried and danced around the tomb. The bodies are then re-shrouded and reburied.
Famadihana ceremonies occur in the region around Antsirabe between July and September only. Local tour operators or pousse-pousse men can help you find one and arrange an invitation. If you receive an invite, it's polite to bring a bottle of rum as a gift for the host family, and to ask before taking pictures. Foreigners are generally warmly welcomed, and most people find that the experience, far from being morbid, is moving and fascinating.