On the same property as the mammoth El Vigía, Museo Castillo Serrallés was the home of Ponce’s rum dynasty, the Serrallés family. Docents lead bilingual walking tours through the lovely Moorish-style castle. When the somewhat exhausting hour-plus tour ends, you can order snacks and drinks at the cafe. Relax on the terrace under the red-tiled roof and enjoy a view of the city below and the quiet burble of the garden’s fountains.
Combo ticket options with El Vigía are available and are perhaps worth getting as they allow entry into everything at the Castillo Serallés tourist complex, including some Japanese gardens and a butterfly sanctuary.