The concept is that skyscrapers are a contrary indicator.
I find these indicators interesting but mostly anecdotal.
My own thesis is that economies and markets for various goods and services have normally bounded rates of growth or decline due to competitive and feedback dynamics. I am working on a project to model these.
Extreme variance from the normal rate of change may sometimes be indicative of a future reversion to the mean.
The extreme growth of banking as a function of GDP in the US is one example. Here is a good paper looking at banking as a % of GDP since 1860.
Technology, finance and un-shakeable faith in the future all coalesce into magnificent projects and works which transcend commercial sensibility, they are collective dreams writ in stone, steel and glass.
The recent opening of the Burj Khalifa tower in Dubai is the latest example of this.
For those wishing a deeper dive on the Skyscraper index the 2005 paper which was the source of the image above is here: "Skyscrapers and Business Cycles". The Quarterly Journal of Austrian Economics 8 (1): 51–74.
My guess is that the Great Pyramid in Egypt, the Mayan pyramids and other peaks, monuments and temples or civic structures in civilizations probably coincided with bubbles as well.
At least with skyscrapers, there are some tangible relics for anthropologists to admire later, much more interesting than say the South Sea Bubble, which mostly created paper and frustration. Let face it, if a bubble has to have economically non-viable externalities, buildings sure beat sock puppets.
The next big towers going up are in China in 2012 and Korea in 2014. Get ready to set your economic stimulators to full stun.
Full disclosure: I am an architecture, archaeology and design fan so probably lack full economic objectivity in this area and willingly look up and cheer on the dreamers while clutching my own wallet firmly on the ground.