What is it about rooftop bars that gets people so happy and excited? The opportunity to look down on the world, like I did from this bar in Madrid on top of the Circulo de Bellas Artes (Academy of Arts).

Or just relax and chill at Good Heavens on top of Fancy Hanks in Melbourne.

Rooftop bars were often space going to waste, and older buildings were usually built strong enough to take the flooring, umbrellas and 30 extra people who head up there. And you will of course check for zoning permits, an extension of your liquor license and safe exits - you did that for your main business, so it's nothing new. 

Start on a budget with strings of coloured lights, portable furniture, canvas awnings and a portable bar. Give it a separate name, like Siglo above The European, also in Melbourne. Turn up the music and spread the word - hey, look at that great sunset!