We currently have 3 large courtyards (one in each 'outer' districts) and 18 smaller ones (4 in each outer district and 6 in the central one). We should at least customize the larger courtyards. And if we have time try some of the smaller ones.. They should follow the themes we had agreed on for the districts (green= nature, blue= water, red.. have we decided on the red?)and they must keep the river/canal they have, beside this I don't see any limitations. (They could also follow the zonning we had agreed on here )
This is not a priority but if someone want to tackle one of those there's enough work for everyone

(I already have a couple ideas but I must first finish that city structure.)