4,000 meters is equivalent to 13,123.2 feet. In addition, 1 meter is equivalent to 3.2808 feet. As a point of reference, 4,000 meters is the approximate altitude of the average skydive, affording jumpers around 1 minute of freefall.
The meter was introduced in the 1790s by the French. It represented one ten millionth of the distance from the equator to the North Pole via a meridian that passed through Paris. The meter was redefined in 1984 as the distance that light travels in a vacuum in 1/299,792,458 seconds as measured by a cesium-133 atomic clock.
The foot has also been refined over time. The U.S. Survey's foot is 1.000002 International feet.