Ya'll don't know 'bout copyright. Quoting parts of TurboSquid which is a massive 3D model retailer:http://support.turbosquid.com/entries/20834766-Copyright-Basics
This applies in the US, Europe, and Australia as far as I know. OP designed and created a 3D model of a building and as such it is copyrighted to him. Yes most people here could make a near perfect copy of said 3D model but that means you are breaking his copyright. The real question is will he actually sue anyone for breaking his copyright.
Lol you have to apply for a copyright
If I make a hovercar and never patent it, Ford can make their own hovercar
Further by the fair usage act you can use a certain percentage of anyone's content.
Otherwise I could never draw another smiley face ever again.