The riding arena is the single most important asset in which a horse owner or equestrian facility will invest. Whether it is an indoor or outdoor, the most important component of that arena is the footing.
The arena itself can be as simple as a designated area sans fencing behind the barn, or as elaborate as a mirrored-wall, wainscoted, climate-controlled indoor facility with natural lighting, and acoustically perfect sound system, an observation deck and lounge areas. Regardless the comfort level of the rider that the various buildings provide, without proper footing, the facility is pointless, from the horse's point of view.