PUNTA DEL ESTE, Uruguay — Daniel Camdessus and Liliana Silberman have spent their vacations here since the 1960s. It’s where they fell in love as teenagers and promised each other that if they ever got married, they’d build a house near the town’s emblematic lighthouse, which sits on a cape jutting into Atlantic waves.

Three decades and two children later, when the Argentine couple finally had the money to design their dream summer retreat, they looked around at the neighborhood’s attractive houses — mostly pitched-roof constructions featuring Tudor or Tuscan influences — and decided to do something completely different.

“We’ve always been interested in modern architecture,” said Ms. Silberman, an interior decorator. “And we had been waiting for a long time to have this house, so we wanted it to be really special and to reflect our sensibilities.”

They hired Moscato Schere, a prestigious architecture studio in Buenos Aires, and asked it to come up with a minimalist, subdued design using stone, wood and concrete. The result — a 2,800-square-foot residence with massive walls made of jagged boulders and a wood-and-concrete terrace that looks like the deck of a sailboat — has been stopping passers-by in their tracks since 1997.