On October 22, 1993, at 1415 mountain daylight time, a Cessna 210, N9653T, landed gear up at the Monte Vista Airport, Monte Vista, Colorado. The pilot and his passenger were not injured and the aircraft sustained substantial damage. Visual meteorological conditions prevailed and no flight plan was filed for this flight which departed Del Norte, Colorado, at 1400. The pilot reported the accident on November 8, 1993, and during that conversation and on NTSB Form 6120.1/2, he stated that he forgot to lower the landing gear. At the request of the Investigator In Charge, the damage was surveyed by a local mechanic and from his evaluation, damage was determined to be substantial. The damage consisted of buckling of lower airframe structural components, wrinkling of both wings, and damage to the horizontal stabilizer. No system failure or malfunction could be identified.