The address is Calle Sarmiento but you'll see this roof top chalet from Avenida 9 de Julio. The best view is from near the Obelisco itself or in front to the McDonald's here.
This small chalet was built on the roof terrace of a nine-story building in 1927 by Rafael Díaz. Díaz owned one of the most successful furniture stores in the city, Muebles Díaz, and famously used the chalet to enjoy lunch and a nap every afternoon.
You can't visit the Chalet but iit will surprise you, perched on top of a downtown skyscraper overlooking Argentina's busiest avenue.