The Gran Vía was cut through the medieval street pattern of central Madrid between 1910 and 1929 — a four-lane boulevard lined with the most ambitious Art Deco, Belle Époque, and early modernist buildings the city could commission, modelled on the boulevards of New York and Paris. The result is one of the great early-20th-century streets in Europe and the heart of commercial Madrid.
The landmarks include the Edificio Metrópolis at the eastern end (with the winged Victory on the roof), the Telefónica Building (Madrid's first skyscraper, 1929), and the Edificio Carrión (with the famous Schweppes neon sign that has lit up Callao square since 1972). The street still works as Madrid's theatre and cinema strip, with the Spanish-language musical theatres centred around Callao.
Walk it end-to-end (about a kilometre and a half from Plaza de España to Calle de Alcalá), or duck in at any metro stop. Best at dusk when the lights come on.