The Beethoven Memorial Museum is the main reason to come to Martonvásár. It sits within the Brunszvik estate and focuses on Beethoven's friendship with the Brunszvik family, especially the sisters Teréz and Josephine. Letters, portraits, family objects, and period rooms give the story a local frame rather than a generic composer biography.
The museum is small, but it is a good one if you care about music history. Combine it with a walk through the park so the visit feels like an estate outing rather than a single-room museum stop.