Wood, plaster, tile, wallpaper, brick. There are so many different ways to cover the walls of a home - some of which are actually the complete absence of covering. While ancient castles hung elaborate tapestries to cover the cold, barren stone of their walls, today many modern designers celebrate the aesthetic of bare concrete. What once indicated a desolate warehouse or unforgiving artist's loft can now be used in conjunction with sleek, modern, stylish choices for a finished look that is anything but dank. Take a look at these apartments and see just how far the idea of concrete has come.