“Considering ideal conditions is a waste of time,” Alfredo Brillembourg and Hubert Klumpner write in their 2005 book, Informal City. “The point is to avoid catastrophe.” The two architects, partners in the international practice Urban-Think Tank, are known for the cable car system they designed for Caracas, connecting barrios in the hills with the city in the valley. Part of the allure of these cable cars, and U-TT’s work in general, is the way they make a virtue of leftover spaces. A shelter for a football field becomes a “vertical gymnasium”. A shelter for street children, built under an overpass, gets another football pitch on its roof. As design critic Justin McGuirk writes in Radical Cities, his survey of urban experiments in Latin America, in “engaging with the informal city, U-TT developed a methodology of maximising the amount of social activity that a tiny plot of land could deliver”. They went small – “strategic” and “urban acupuncture” are the terms du jour – looking at what the city had become, and what individual neighbourhoods needed, rather than masterplanning a cycle of demolition and straight lines.