A construction crew completed a retrofit on Citicorp Center in NYC over a few months, and the project was kept secret for almost 20 years after its completion.

A construction crew completed a retrofit on Citicorp Center in NYC over a few months, and the project was kept secret for almost 20 years after its completion. https://en.wikipedia.org/wiki/Citicorp_Center_engineering_crisis https://en.wikipedia.org/wiki/Citicorp_Center_engineering_cr...