A little thought exercise. I don't think we'll ever see this civ due to its small size, its arguably low priority compared to numerous others, and the mod's general move away from eurocentrism. Still, this is intended as a "serious" approach as to how this could be represented on the larger map.
Belgian Civ
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Spawn: 1830 AD at Brussels.
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Territory: These tiles plus Belgian Congo, on the big map:
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UP - The Power of the Flat Country: Historical coastal tiles also counts as water tiles for ship and city purposes.
-A UP that exists entirely to allow Brussels to exist inland and two tiles away from Amsterdam, though it also has the side effect of allowing you to settle Leopoldville inland if you so choose.
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UB - Grand Square: Replaces Palace. Other civs are willing to trade resources at a lower price, unique traded resources provide their unimproved base yield to the city.
-English name so as not to choose between Grand Place and Grote Markt.
-Yes, I know that Belgium also has a proper Palace, but I wanted an economic UB, and this one largely predates the spawn date so it should be there from day one.
-As an example, the traded resources effect would give you +1 
from Wheat, +1 
from Iron, etc.
-I wonder if something should be done with corporations - their resource consumption is directly at odds with the UB but Belgium is unambiguously a capitalist country so the player shouldn't be discouraged from blocking them. Yet I'm reluctant to add another effect, so maybe something should be done with a modern great wonder that would give "Corporations don't consume resources in the city", but I'm not sure which one would fit. That, or just precise that Corporations do not affect the UB's bonus even if the resource is otherwise consumed.
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UU - Force Publique: Replaces Rifleman. Can enter Marsh, Jungle, Rainforest. Can build Plantations, Slave Plantations.
-I don't think Belgium would have the time to reliably get Slaves the normal way so this is another way to get Slave Plantations.
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UHV1 - The Long Nineteenth Century: Make Brussels the city with the largest combined number of Merchants and Engineers in 1908.
-Refers to Belgium's role in the Industrial Revolution, which would effectively encourage you to build lots of economic and industrial buildings.
-Settled Great Merchants/Engineers would count.
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UHV2 - The Congo Free State: Control Congo and X Rubber Slave Plantations in 1908.
-The infamously brutal exploitation of the Congo by Leopold II makes the use of slaves feel justified.
-The two UHV have the same date so that you can't use Egalitarianism to get more Engineers.
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UHV3 - European Integration: Build Berlaymont, have Defensive Pacts with at least 40% of European civilizations and allow no communist civilization in Europe by 1992.
-The date is arbitrary, could be any other significant date in EU history.
-The communist part is there to make the diplomacy slightly harder and simulate the EU's attachment to liberal capitalism. It could be replaced with some other civics-related goal.
-This is a "by" UHV. It can be completed earlier than the deadline, since I'm guessing waiting this long would be a bit boring.
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A possible special rule to further help the civ: Civilizations with one core city receive +1
per specialist in the city, in the late game (modern era or late industrial). This should also help make Republic obsolete (the two bonuses aren't cumulative) and help simulate small, dense civs.
I don't think the Atomium needs a new effect to synergize with Belgium, though that could be a nice bit of flavor. Additional
from Defensive Pacts?
