21 Turtle Creek — known by insiders as simply “21” — is one of Dallas’ earliest residential high-rises. Built in 1963, its midcentury minimalism is fully embraced but it is also imparted with the upscale, elegant atmosphere expected of a Turtle Creek address. One-, two- and three-bedroom homes are available, set amidst some of the nicest grounds along Turtle Creek. (The pool is especially picturesque here, under mature trees.) Sleek, solid, quiet: This is one of the bigger buildings on the boulevard, but its residents, from all walks of life, enjoy very easy living.