Dedicate your second day to exploring the rich art and culture of Gran Vía. Start your day by visiting the Museo Nacional del Prado, one of the world's most renowned art museums. Marvel at the impressive collection of masterpieces by artists like Velázquez, Goya, and El Greco. Afterward, head to the nearby Museo Thyssen-Bornemisza, which houses an extensive collection of European art. In the evening, catch a show at one of the many theaters along Gran Vía, known as the Broadway of Madrid.