Two streets in one. The eastern, theatre end (Callao toward Plaza de España) is Madrid's Broadway — musical billboards, the Schweppes sign over Plaza del Callao, a real after-dark buzz. The western, retail end toward Metropolis is a chain-store crush you walk through, not for. The trick is to look up: the Belle Époque and early-skyscraper façades, best caught from the Calle de Alcalá corner at the Metropolis dome around golden hour.