The House of Manannan is an award-winning heritage attraction housed in the former Peel railway station building on the harbourfront. The exhibits tell the story of the Isle of Man from Celtic and Norse times through to the modern age, using dramatic reconstructions, artefacts, and audio-visual presentations. The section on the Viking settlement of the island is particularly good, and the reconstructed Viking longship in the main hall is impressive.
The museum covers roughly 1,500 years of history in a relatively small space, which means it moves quickly. The quality of presentation is high — Manx National Heritage has put real effort into making the island's complex history accessible. Combined with a visit to Peel Castle, which sits just across the harbour, the two attractions give you a thorough grounding in Peel's medieval heritage. Allow two hours for both.