This list omits Sur (1987) and Estamos rodeados (1991). What the heck -- buy 'em all. But if you have to decide on a handful of albums, get these:
Aquello (1980): His last "European" album could not have been more Uruguayan. Includes "Los Olímpicos" ("The Olympians"), which compares the Uruguayan soccer Olympic champions of 1924 and 1928 with today's immigrant workers, the "shameless bunch who show up for the leftovers." Future Gipsy Kings' drummer Jorge Trasante adds percussion.
Siempre son las cuatro (1982): More than 50 guest musicians add to a contrast between popular anthems ("Adiós Juventud," a murga about the loss of youth) and avant-garde experiments à la the Beatles' "Revolution 9" like "Desde aquí se ve," which collages children's voices, a drum machine beat, a woman who reminds us of the expiration date on a coupon, and a phrase repeating "From here you can see/It's so nice to have windows" over and over again. A classic.
Brindis por Pierrot (1985): The album that changed it all. A collection of mostly previously released murgas and candombes. The party album.
La Margarita (1994): Roos's adaptation of sonnets by Mauricio Rosencof, a member of Uruguay's tupamaro (urban guerrilla). Rosencof would write while imprisoned and between torture sessions, and his wife would take them hidden in his laundry. A moving album about the art of survival and innocent love.
Si me voy antes que vos (1996): The title song is one of the best things he's ever written. The album opens with a band version, and a few tracks later there is a haunting, more intimate version gloriously sung by Argentine goddess Mercedes Sosa. However, Roos hates the final mix and dreams of re-releasing it one day. What does he know?
