The Nelson Rooms is a grade II listed building in Monmouth, Monmouthshire, Wales. It is in the historic Glendower Street and Agincourt Street neighbourhood, within the medieval town walls. The building initially served as a gymnasium and was a gift from Lady Llangattock to the town of Monmouth. In 1924, after the benefactor's death, it reopened as the Nelson Museum, and showcased the collection of memorabilia related to Admiral Horatio Nelson that had been amassed by the baroness. The Nelson Museum moved to new quarters at the Market Hall in 1969. The former gymnasium and museum is now an apartment building.