My first true survival base was on a server. This would have been late 2014. (I started playing mid-to-late 2013, but I had only played exclusively in creative). It was a thin birch tower, with the top level being made out of leaves (believe it had around 4 stories); about 50 blocks away was an abandoned, unfinished structure which made for a bit of an eyesore (I couldn't remove it because there was grief protection). It was walking distance from spawn. I lived there with my sister for a while, before she got sick of me leaving doors open (she was deathly afraid of mobs) and moved about 70 blocks away, building what we now call "The Noob Cage", because it was quite literally a 5x5 cage made from oak fences.
I had a guy move in with me and the base expanded greatly; it gained a basement, an indoor farm, and an entirely new structure (which required demolishing a hill) wedged between the birch tower and the Noob Cage. However, he stopped coming around after a while, and he also left claims behind on parts of the base; claims that I couldn't remove, give other people permission to use, or even build on if I recall correctly. So I moved way from that spot... I think I was kinda just a nomad for while, before the server reset...
Incredibly detailed map of the base's general area:
I unfortunately didn't know how to take screenshots at the time, so no pictures