The very first 737 model was the 737-100. It was first ordered by Lufthansa in 1965. The -100 was finished on January 17, 1967. It entered service in 1968. The aircraft is the smallest type of 737. Only 30 737-100s were ordered and delivered. No 737-100s are still being used by airlines. The 737-100 prototype is in the Museum of Flight in Seattle.