cool,there are things you can do in the meantime while you look
for textures,..
I'd bring back the river but not too big as it looks good
in aerial shots,a bendy one like the thames ,plus its a great filler.
If you have s.up 6 you can download loads of materials,try using
paving, concrete ,asphaltcladding materials on buildings and
if you have any flat roofs like warehouses etc put in some
skylights to give it some detail.You could also try doing some land
in grass ,sand and gravel all mixed up to make it look more real
while your waiting to fill the city with buildings.
so in you aerial shots its looks like actual land
with construction and it will connect your c.b.d
with the industrial part.