The world I have since alpha consists of a gigantic city spawning continents, passing through the Nether even and going forth to 1.8 areas, containing hotels, castles, mines, houses, bases, etc. All legit, all built by me alone.
Everyone knows about making their own skin through pixel art (so i would hope) so i made exactly that, only 126 blocks tall, one less than max block level not counting bottom bedrock. It was instaed of 1x1 per pixel, it was 4x4 (i think). It was also 2 of them, one with a bow and arrow, another with a pickaxe. Yes i'm sorry it was creative...
Not quite as good as some things on here, but still pretty big
Not really. My friend was the one who ran the server and he used his mod powers to level out the area for me. Him and a few other people also saved me time by giving me items that I needed. Plus my friend saved me time on the houses by copy/pasting them for me after the first was built. I'd say about 90% of the actual building was me working on it, the other 10% was help from friends, and even then we didn't fill up the entire 450x450 area (I was leaving space for others to build stuff, such as someone building a large tower). A map that I made before I built the city. The outer wall ended up squarish instead of round, and the beach wasn't added.
#4 - Farris floating pyramid temple (not showing it all, just half of it, other half is left behind - if I remember I post the other side of it with 1 120x120 base pyramid + a 64x64x64 octahedron, both with inside details and stuff)
biggest build I am making (if you consider a kingdon with everything within connected) is a 1500x1800 kingdon
biggest massive structure I am still building, a 200x100x200 castle, it is some 7% completed by now:
castle entrance update (floor, tower and stairs up, sure, it is less than 10% of the entire castle as castle will be built over the floor, under will be like a set of pillars with a small village inside the walls, as I mentioned before, will be a 100x200x200 castle, the pillars and village are also part of it.)
This is a house floating at hight 131. It is a big floating house with lots of redstone. about 45 wide,120 long and 20- 45 high. all redstone hidden so it's not ugly. This took about 4 days so far and i'm still working on it. My f2 button doesn't work work so no screen shots yet.
Well... for size it would probably be the smugglers cove I made by hollowing out a mountain range... it isnt finished.
For complexity, and a runner up for size, is a gothic castle with a facade made from 4 hexagonal towers (completed with hexagonal rib vaults) and an arcade with lots of tracery hanging beneath said towers.... I am still trying to figure out how I want to make the gardens and aqueducts