That is Kings Landing, the capital city of the Seven Kingdoms, from the book series A Song of Ice and Fire by George RR Martin, as well as from the TV series Game of Thrones, which is based on the books. The three largest structures of note in that image are The Red Keep, the large castle at the right side of the picture, the Great Sept of Baelor, the white circular dome and spires in the midst of the left side of the picture, and the Dragon Pit, that somewhat destroyed looking dome in the upper right. Obviously you have the docks at the bottom as well. That image came from the massive build group, as well as the server known as WesterosCraft. Their goal is to create all of the continent of Westeros in Minecraft, and potentially move onto Essos.