Fences were never built to prevent trespass by hot-air balloons transiting across the sky. The ground chase cars are more easily foiled, however.

This photo was taken by a Hasselblad 500C and Carl Zeiss Planar 1:2.8 f=80mm lens using Kodak Portra 160 film, the negative scanned by an Epson Perfection V600 and digitalized with Photoshop.