Eldorado

Not to be confused with the older Eldorado made in 2012 by a random Facepuncher

Eldorado was a massive build project created be Leuphou, where he covered an entire continent in various ore blocks, the majority being gold blocks. It was started on July 29th, 2019, and was griefed sometime in mid-January 2020.

Founding
Leuphou was bored of building and repairing highways, so he decided to start covering an entire island in gold blocks. Eventually he also got access to dupes and was able to make massive amounts of materials for the base. In the build, the ground blocks are all gold, trees and cacti are made out of iron and emeralds, lava is made of redstone, rivers are made of diamond, and some of the surrounding ocean is covered in lapis. Other builds include a giant gold bird flying above the island, and a gold cavern with a gold pyramid filled with chests of gold under the island

Completion, Leak, and Grief
After the island was completed, Leuphou was bored of 2b and decided to leak the coords himself via a puzzle involving the golden ratio on November 26th 2019 (puzzle can be found here). After a few months, nobody had destroyed the base still, so Leuphou directly leaked the coordinates himself on the subreddit on January 14th 2020. The base was griefed within a few days by an unknown individual.