If you want to build infrastructure, get an undead creature or construct that can make perform checks (Dread Warrior, Warforged, Skeleton with Awaken Undead, whatever) and can follow plans. Have a construction team plan out the infrastructure you want, then give your undead guy a Lyre of Building (he only needs a +5 bonus to just take 10). Once such worker can work 4800 man hours per day and keep going continuously. Even just one of these can handle roads, sewer systems, and so on, but if you get a few more you can build plenty. And don't forget, you can supply your city's water needs with a few Decanters of Endless Water permanently set to geyser mode.
Note that a Binder who can bind Zceryll with sufficient binder level can chain summon Genies for infinite permanent wood products. You can now use Bronzewood (hard as metal), Darkwood (half weight) and Wildwood (regenerates) to build infrastructure and housing with your lyre playing builders.
As a bonus, construction noise in your magical world will not be pounding pile drivers. Instead, it will be beautiful lyre music.
JaronK