Using data from Turner & Townsend, Curbed recently reported that the most expensive city in the world in which to build is now San Francisco. On average, it costs USD 417 per square foot. San Francisco is followed by New York ($368 psf), London, Zurich, and Hong Kong. New York took the top spot last year, but San Francisco shot up this year because of, you know, tech.
This number was calculated using a blend of six different types of construction, everything from apartment high-rise and prestige office to general hospital and warehouse distribution centers.
Now, I'm not exactly sure what this number includes. But I'm assuming it is only direct construction costs and doesn't include (contractor) general conditions, land, or any soft costs, which are all significant. Once you add in these other cost inputs, I am sure that you can start to see how things -- including the cost of new housing -- can quickly escalate.