Madrid is a very easy city to explore on foot as most of the key sights -- palaces, churches, and museums -- are closely grouped in and around the central narrow-alleyed Austrias district, and the city itself, though high up, is mostly flat. Plus, you don't have to go to the periphery of the city to find beautiful green areas and a bit of respite from the urban hustle. The Retiro and the Casa de Campo can both be reached in 15-30 minutes on foot from the Puerta del Sol.
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