Fortifications are militaryconstructions designed for defensivewarfare. They have been used for many thousands of years, in a variety of increasingly complex designs. The practice of improving an area's defense is also known as "fortification". Many military installations are known as forts, although they are not always "fortified".
... BBC1 and BBC2, using terrestrial signals, and this is seen by some as influential (to a certain limited extent) in promoting the take-up of digital television.
BBC ...