The Ionad Árann in Kilronan is a small heritage centre with exhibits on the geology, archaeology, and folk traditions of Inis Mór. The centrepiece is a screening of Man of Aran, Robert Flaherty's 1934 documentary — or rather, semi-documentary — about island life. Flaherty staged much of it: islanders who had not hunted basking sharks for generations were recruited to do so for the film, and the thatched cottage shown was not a typical home. None of which makes it less interesting; watched as a record of what someone in 1934 thought Aran life should look like, it is revealing.
The film runs about 75 minutes. The archaeological exhibits are informative and worth a look before heading out to the forts — having a sense of the Bronze and Iron Age context makes Dún Aonghasa and Dún Dúchathair more legible. Entry is modest (around €5). In summer, check screening times when you arrive.