Here's something I've been working on most of the day, probably going to take me a while to complete.
Currently not using any mods(just a texture pack and a mini-map, no mods that'll actually help building), been messing around on creative mode, superflat. Got lucky and spawned inside a huge npc village, which I haven't messed with at all yet, and started building this right above it.
http://imgur.com/a/U9R2T
Was originally planning on making it more like
http://wiki.guildwars2.com/images/a/..._Reach_map.jpg, but I realized that angled corridors would be extremely annoying, so I only went with 4 instead of 6. Still going to have an upper city area eventually, and probably a large, open plaza area in the middle of the bottom level. Going to go back in and add more detail to the area once I'm done building the other 3 districts. (so far, there's a small fountain on the main road near the gate, but in both screenshots it's blocked by the bridge.)