Complex sentence: The cave was first scientifically investigated in 1885, but was not opened until 1933, and also was used as an air-raid shelter during World War II. A museum was set up on site by the then curator of Natural History Dr J.G. Baldacchino.
Split into simpler sentences: The cave was first scientifically investigated in 1885 but was not opened to the public until 1933. It was used as an air-raid shelter during World War II. A museum was set up on site by the then curator of Natural History Dr J.G. Baldacchino.