how did the romans built cities and showed us how to organize these?
There's a variety of topics here -- how Romans built cities, roads, aqueducts, and other things:
http://www.google.com/#sclient=psy&hl=en&q=how+romans+built+cities&aq=f&aqi=&aql=&oq=&gs_rfai=&pbx=1&fp=280187d6f0589da0
Read lots and read carefully.