Government Buildings

Hi,


How often can you build Government Buildings after you build the Plaza? I will build the Chambers or another one but then the option to build more is not optional. What am I missing. One per era? Or depedant on population in capitol?How can you build all of your Gov Buildings in your capitol as quickly as possible?

Please help.

I didn't find the right solution from the Internet.

References:
forums.vbmmnatics.com
Industrial System Video

Thanks