Go in front of the "Gran Vía" metro station, to a point known as "Red de San Luis" because of the fact that it was once where several of the capital's streets intersected. This is where the second part of the "Great Way" starts, which was completed in 1922, goes all the way up to Plaza del Callao, and is considered the so-called "boulevard", named Avenida de Pi y Maragall in honor of the first president of the Republic.
You'll immediately notice the building at number 28: it is the Telefónica Building, which was designed in the late twenties by an American architect, and in fact looks like a New York skyscraper. Just think that when it was built, its 81 meters made it the tallest building in Spain; but only a few years later during the civil war, it also became the preferred target of nationalist troops advancing toward the capital.
A little bit further on at number 32 you can see the so-called Madrid-Paris Building, famous for being the home of Madrid's first shopping center and the capital's first escalator. Recently a famous clothing store moved to its first five floors, attracting really long lines of customers. The Phoenix on its central dome was the emblem of an insurance company which has since gone bankrupt.
This stretch of the Gran Vía is nicknamed the "Madrid Broadway" because it has eleven buildings for entertainment. At number 31 you can admire the Palacio de la Música's façade with its impressive parade of columns. At first it was a concert hall, then it became a movie theater until it was closed permanently in 2008.
FUN FACT: the megastore at number 37 was once home to a movie theater, the glorious Cine Avenida. Between one garment and another, you can still admire the ancient entrance with balconies, mirrors on the ceiling, and magnificent staircases!