If you only had one day to spend in Barcelona, exploring Montserrat and the Sagrada Familia would be the way to go.
Leave the city behind and bus to Santa Maria de Montserrat monastery for a look at its Gothic-Renaissance architecture and hoards of priceless art.
Then it's back to Barna, and the wonderful Sagrada Familia. Admire Gaudí's masterpiece, hear its history, and learn about its construction.
There's even time during the day for a tasting of regional liquors. Salut!