There is some evidence to believe that Nehemiah (the book) was written by Ezra. Yet we don’t call it 2 Ezra. Go figure.
Nehemiah mainly describes the renewal of the covenant between God and His people. The vehicle for this is the rebuilding of the walls of Jerusalem. The terms of the covenant thus described are protection for worship/obedience.
A church I went to a few years ago was trying to raise money for some building renovations and upgrades. Since Nehemiah, even more than Ezra, covers challenges faced by those who want to build for the Lord, the pastor conducted an extended sermon series on Nehemiah. For some reason, this disillusioned me to the idea that sermons were always pure expressions of holy teaching, motivated by nothing but the desire to edify and instruct the congregation. It wasn’t necessarily a bad thing, but it served as an eye-opener to me that churches are human-led organizations with agendas and interests of their own.