Boeing was looking at designs for aircraft which flew short distances. Boeing wanted to make another aircraft to replace the 727 on short flights. It began designing the 737 on May 11, 1964. Boeing did a lot of research and found that airlines wanted an airliner which could hold 50 to 60 passengers. This airliner would also be able to fly routes long. Lufthansa was the first airline to order a Boeing 737 on February 19, 1965. They ordered 21 aircraft, worth $67 million (1965, $190.28 million in 2008). After Boeing spoke to Lufthansa in winter 1964, they made the 737 bigger so that it could hold 100 passengers.