Standing at the heart of Madrid is the Museo Nacional del Prado, renowned for its array of masterpieces by Velázquez and an unrivaled collection of Goyas and El Grecos. Nearby, the Centro de Arte Reina Sofía displays works by Miró, Dalí and Picasso, including the latter’s “Guernica.” To the east of the great central thoroughfare, the Paseo de la Castellana, lies the chic residential district of Salamanca, which not only contains much of the city’s most desirable real estate but also a majority of its upscale boutiques and galleries. Madrid’s character owes much to its location 2,188 feet up on Spain’s central sierra, which ensures a sunny climate but also freezing winters and scorching summers. I prefer to visit during the spring or fall, either April-May or September-October. But travelers particularly interested in museums and shopping might enjoy January most, when top sites are uncrowded and stores have their best sales.