Transparent aluminum could be used to construct towering glass-walled skyscrapers that required less internal support.

For decades, chemical engineers have dreamed of a material that combines the strength and durability of metal with the crystal-clear purity of glass. Such a "clear metal" could be used to construct towering glass-walled skyscrapers that require less internal support.

Secure military buildings could install thin transparent metal windows impervious to the highest-caliber artillery fire. And think of the monstrous aquarium you could build with this stuff!

Back in the 1980s, scientists began experimenting with a novel type of ceramic made from a powdery mix of aluminium, oxygen and nitrogen. A ceramic is any hard, usually crystalline material that's made by a process of heating and cooling.

In this case, the aluminum powder is placed under immense pressure, heated for days at 2,000 degrees C and finally polished to produce a perfectly clear, glass-like material with the strength of aluminum.

Known as transparent aluminium, or ALON, the space-age material is already being used by the military for making armored windows and optical lenses.