La Muralla has a gorgeous terrace and is perfectly located at the end of Cava Baja and is a nice stop off point walking from the Plaza Mayor to the La Latina area (it's also just a few minutes walk from La Latina metro). It's a gorgeous area, still very typical old Madrid even if it has been quite gentrified in recent years. La Muralla has been in the same hands for many, many years (the owner was a waiter there when I lived there 20 years ago and still remembers what I like to drink when I go back!) the free tapas and raciones are very generous and the menu of the day (only served inside) is really good - typical food, well done, and very reasonable. Can't recommend it too highly.