if you won a community auction for a small empty building  in the community on one condition.....?

A community kitchen.  Not only would I teach basic cooking and food handling but it would be a place that allotment holders could come and can or otherwise prep their produce and get a certificate that the premises met the city council's standards for small-scale commercial food preparation.  My local council requires a minimum area of kitchen space which most flats/apartments don't reach.  It's such a shame as there are many very good jam makers and other canners who would like to be able to sell their surplus.  

What a lovely question.

I would wanna create a community maker space like Artisan's Asylum in Boston where you can learn to make lots of cool things. 

I would probably turn the building into something that they really need such as a community hub,

Who judges whether I've helped the community?

I'd probably turn it into a Quiet Center, where people can come to read, write, or think without being bothered by others in the household.