What is this ancient Chinese building?

I read a story about a famous ancient Chinese architect (or maybe engineer) which is apparently true, but I cannot remember what the building in the story was. I do know that it still exists today.

The story is as follows:

Brilliant architect is commissioned to design this building. He (being so brilliant) calculates the exact number of bricks required to build it, and writes the number down for a messenger to take to the brick-making guy. The messenger suggests that perhaps he should order a few extra, in case he mis-calculated. As a joke, the architect adds one brick to the order.

Apparently, this building still stands, with the one extra brick precariously sitting on the middle of a ledge.

Anyone know what the heck I’m talking about here? Anyone know of any websites with pictures of this building?

Thanks.

Forget the building and the architect, I want the crew that can move a load of bricks and build a wall without breaking anything.

I remember hearing that story on a ‘Discover in the Classroom’ episode on China that I watched while stalling going to work because of it’s lack of commercials. I remember that it was a fort, on one of the spice trails at the western end of the country I believe. I want to say the ‘Jade Gate’ but I have a suspision that it was part of a segment that came just before it in the program.

It seems to be a fortress in Jiayuguan on the Great Wall, according to this site:

http://www.ipix-china.com/greatwall/greatwalk-e/logs/part3/part3.htm

It appears to be down now, but here’s google’s cached copy.

The brick legend is about half way down the page.
BTW, I found this with a google search on “brick china legend -tea exact”.

Arjuna34