The earliest humans to take to the sky did not do so in anything that resembles the aircraft and large planes that sit at airports today. Early flight was such that humans did not require an airport with extensive metal detectors and air cargo security since flight was made by simply hydrogen-filled balloons. Although there had been designs created for hundreds of years regarding flight, the first people to do so regularly were the French in the late seventeenth century who began experimenting with hydrogen and its properties. Some balloons were even used in wars like the American Civil War.