As y'all probably know speculation about Co-Ordinates found in "Future Boy Zoltron" and "Last One Out of Beach City" leads to somewhere in Brazil and a location that was left out on Buddy's Map, but why?
Pearl blatantly pointed to all the built Gem Locations on Earth, but left out that one could it be because something Dangerous or something she wants to forget is there.
Now, evidence is a key factor here and of course there is limited amounts BUT I have some. Firstly if Pink Diamond was the Diamond of Earth, she most likely would have a main base set up there or at least an initial base which I believe to be in Brazil where Pearl didn't mark, and why? Because the Ancient Colony Ships where estimated to be located in Columbia, South America a short distance (to a Gem) from the location shown on the Moon Base Map. So if Pink Diamond was shattered early on wouldn't it happen at one of the first bases or temples made for Pink Diamond.
To clear things up also, even though Ruby called the Moon Base Pink Diamonds Era 1 Moon Base, this doesn't mean she was shattered there or stayed there after the colonisation began, as by the consoles use it seems like a base set up before the Colonisation began an Outpost if you will... Along with this to save confusion, I don't think Pink Diamond had too much built on Earth before she was shattered, and after which I believe Blue Diamond took over as suggested to in the Answer, the Crystal Gems and Rebellion had started by that point, and explains why most of the structures carry a Blue theme, as these where built as per instruction and for Blue Diamond before it was finally abandoned for the Cluster Project.
To Sum Up, when arriving on Earth the Gems first arrived in Columbia (Well a location equivalent to Columbia in South America) to begin a colony for Pink Diamond hence the Pink Themes of the Ancient Colony Ships. After a little exploration a base or set of buildings was initialled a distance away from the landing site in Brazil, where Rose Quartz challenged Pink Diamond and shattered her, but before this of course the Prime Kindergarten was built somewhere in America (evidence by how it's a train ride away), and it makes sense to keep the thing sucking out life from the Planet away from your main base. After the shattering Blue Diamond took over the colony, hence the lack of Pink Theming in a lot of the Gem Structures which instead have a blue theme.