In Changsha, China, one of the fastest built buildings is making history. The Broad Sustainable Building Co. – a prefab construction firm – managed to erect a 57-story skyscraper in just 19 working days. This shocking feat was discussed worldwide and took up top headlines in sites like The Guardian and New York Post. Continue reading to find out how a construction company managed to achieve this.  What was the secret?  The secret was modular construction. Noted by Xiao Changgeng – the vice-president of the Broad Sustainable Building Co. – the company put up the rectangular, glass and steel Mini Sky City, assembling three floors a day, using a modular…