Yeah it is interesting that we admire the huge buildings and architecture of past large civilizations but realistically they were almost always built on exploitation and slavery.Malians build many building when they were wealthy, but all that vanished and the archeologist rebuild that famous Malian mosque. If you don't have money to build mega building and project you would not have them. Italians had the money and hired the best designers, your average Somali state in 1880 could do that for the lack of money. Beside that, if you look at any big well desinged European city, you will find that it was financed with stolen money or slaves. St petersburg for example was build with slaves and serfs, without them, the Russian state would not have build such great city.