This is the approved revision of this page, as well as being the most recent.
Who is obligated to contribute?
- Anything needed for protecting of the city is provided by all residents except Torah scholars be cause their Torah protects. However, if the city needs a communal resource fixed then even Torah scholars are obligated to contribute. Nevertheless, the Torah scholars should not perform menial labor in front of the public eye. 
- A Torah scholar who disgraces mitzvot and lacks fear of Hashem is considered one of the lowly members of the congregation. 
Obligation to Build a Shul
- Gemara Kiddushin 70a, Rambam Sanhedrin 25:4, Shulchan Aruch Choshen Mishpat 8:4
- Shulchan Aruch YD 243:3