Everyone's favorite, Museo del Barro displays everything from modern paintings to pre-Columbian and indigenous crafts to political caricatures of prominent Paraguayans. Take bus 30 from Oliva and get off at Shopping del Sol . It's three blocks from there off Callejón Cañada.
Stay on the bus and you'll pass Parque Ñu Guazú , a pleasant place to pass an afternoon, with lakes and walking trails.