Building upward

I was experimenting with building today, and I'm wondering if there's some easy way to know how many prims can fit in my 512. It seems like some areas can hold more than others, or maybe it's just my imagination.

Also, is there a certain height at which the property stops being yours? Like if I build 3,000 feet in the air, is that still considered my property? I've noticed that on properties I'm not allowed to enter, it's only near the surface. I can still fly over them, and enter the upper floors or land on the roof if the buildings are reasonably tall.

512m give you 117 prims. Building much above 700m causes things to get very wonky (at least it used to). The property is yours up to the top of the sky, the ban lines only go to 40m above ground.

Okay, that makes sense. 117 prims isn't really a lot once you have a house there. I was able to build at 3,000m but not at 5,000m. I didn't test to find out the exact height was where my stuff was disappearing.

Another question I had, which I'm pretty sure I know the answer to: If you build something that slops on to your neighbour's property, they can just return the item to you, right?

The "root" of a prim is what decides on which parcel it lives and only the parcel owner can return or delete it. The root is usually the geometric center of a prim; for cubes and spheres this is pretty easy to see, for more complex shapes not so. When you edit a prim though, the X Y Z number up top show the exact location of the root.

You could build a 10m rod that overhung your neighbors parcel by 4.9 meters and still "live" on yours. This is considered rude and is against the rules, too. If you are building at high altitude, the neighbor may not notice or care.

One other relevant thing which you didn't ask but I'll answer anyway. Any parcel you own in a sim contributes to your prim allowance whether or not they are adjacent. Thus, you could buy another 512m on the other side of the sim, put nothing on it and have 234 prims to use on your main parcel.

Happy building.

You can build normally up to 768 meters.

From 768 to 4096 meters, any time you move anything in a build it will drop to 768 meters.
Above 4096 meters, no objects not attached to avatars can exist.