Sammy Sosa -- I Need Fancy Art to Fill My Fancy House

Sammy Sosa got his aristocrat on at a fancy shmancy art soiree in Miami Sunday night ... where TMZ has learned, he rubbed shoulders with other rich people looking for expensive pieces of art to fill their mansions.

It all went down at Univision star Raul de Molina's 12th annual Art Basel celebration -- where we're told Sosa rolled up in a white Rolls Royce -- and hung out with other celeb guests like NASCAR driver Pablo Montoya, artists Ruben Millares, Liu Bolin and Antonia Wright, and Disney star Sofia Carson.

The slugger just purchased a $7.6 million. 7,272 square foot home in Golden Beach -- which is one of the few places in Miami where you can own ocean front property ... and naturally he needs some equally impressive art to fill those walls.

No word if Sosa actually purchased anything at the show ... but a little culture never hurt anyway.