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.