You must have seen those long protruding entities issuing out of the top of very tall buildings. They are called spires. But why do all tall buildings almost invariably have them?
Many a fancy modern skyscraper in many a fancy city increasingly seem to be sporting those fancy spires, the first significant use of which was recorded in the U.S. in 1930 for the Chrysler Building. Usage of spires have increased off late in the U.S.; still, it's third in the list of the highest average spire or vanity height in buildings topped by United Arab Emirates followed by China according to the Council for Tall Buildings and Urban Habitat (CTBUH). Aesthetically pleasing alright, are they merely for fancy pleasure or they have the functionality to them as well?
Height Bragging Rights
Functioning like a 'hat' in an architectural sense, this extension by way of spires is an elegant culmination to the otherwise unimpressive flat-roof adding to the height of the building with economic viability as the mast is certainly cheaper to build than habitable floors or even a concrete core. It's very much with the aim of elevating their buildings higher than others - to draw more prestige value - that developers often put in the spires in the plan.
Slender Decorative
If you come to think about it, remove the spires from famous buildings that you are aware of and they will somehow look incomplete as if something is missing. So it constitutes the architectural visual aesthetics and in that way necessary. In itself, they do not necessarily add structural integrity to the main building. In some cases, it rather distracts- any additional load permanently attached to a tall structure adds to the seismic weight, resulting in extra higher lateral forces on that building during an earthquake.
Conducting Rod
You might have come across tall constructions specially Cathedrals built during the Middle Ages at least in pictures and may reconnect distinctive spires protruding upwards from the tops of those buildings. Now they had functionality then, that of being the Lightning rod so that the building is properly ' earthed'. Technology has moved on since so we don't exactly need a lightning rod to withstand lighting attacks, but the practice of putting in spires nonetheless seems to have been retained.
Broadcasting
Some of these buildings fitted with spires are made with a particular purpose. Television signals and radio waves can be broadcast via these spires which functions as antennas and masts being equipped with signal transmitters. The most famous example would be the telecommunications tower of Central Poland, Warsaw radio mast, which at 646.38 metres, was the world's tallest structure from 1974 until its collapse in 1991.
