So I'm working on my own new civs, and most of the leaders, unique units, and unique buildings are simple re-skins. For some of the unique buildings, I would like to use re-skinned aqueducts and walls. But it looks like these buildings, due to the special circumstances in which they are depicted, are trickier to re-skin than, say, a barracks. If I copy over the building's directory into the new Arts directory and make the normal adjustments, the building looks different in the Civilopedia but not in-game.

How would I go about giving a civ a reskinned aqueduct or walls for its unique building, so that it appears as it should in-game?

*crosses fingers that it won't be ridiculously difficult*

if i'm not mistaken, the aqueduct artwork is conrtolled not by the nif, but y the LSYSTEM. An no idea how to edit that.

I guess, it's something with the artstyles.
There are different artstyles in the game, like asian or european, so the cities look different (which civ uses which artstyle is defined in the CivilizationInfos).
I don't know, if this affects also the normal buildings (i thought only the citysets), only the aqueducts of some civs should look different.
In most cases, ArtStyleEuropean is the standard artstyle, which is used for the standard buildings, so try to start a game with germany, england or france, and see, how it looks.

It doesn't look like the artstyles are responsible - I get the same results with ARTSTYLE_EUROPEAN, ARTSTYLE_MIDDLE_EAST, and ARTSTYLE_SOUTH_AMERICA. I think mechaerik hit it on the head, though: it seems to be an LSYSTEM issue.

Looking around, I eventually found in CIV4ArtDefines_Misc some "MiscArtInfo"s that set up Aqueduct wells, segments, and endpieces... but changing them at this level will likely change all aqueducts in the game.

Further evidence that it probably involves the LSYSTEM is the Celtic Dun, a Walls replacement. It has its own LSYSTEM to accomplish the custom graphics: LSYSTEM_CELTIC_DUN. I wouldn't be surprised if a custom aqueduct would require something along the lines of LSYSTEM_FANCY_AQUEDUCT.