Fortnite’s battle royale map got a big overhaul at the start of the season due to “The Device” event causing a massive flood, and it has continued evolving ever since. In its latest update, Epic Games added an area previously hidden underwater, and it appears to essentially be the lost city of Atlantis.
Technically, this area is called Coral Castle, and it is located north of the Sweaty Sands area. Previously covered with water from the flood, it has receded enough to show off a glorious and very small hidden city. The centerpiece here is a breathtaking castle, as you can see in the video below. There are plenty of points for cover in the castle, making it ideal for defending against multiple enemies late in a match.
From the video, it appears the castle was originally called “Carl.” This is almost certainly a reference to the popular Walking Dead meme.