Present Day Height Rules For Building.......

When I first came on SL I believe it was recommended not to build above 764 meters or something like that........has that been increased to 4000 meters?......and if so will SL teleport someone that high?.......

At one time the build limit was 768m, now it is 4096m. Objects placed higher will not stay put.

https://wiki.secondlife.com/wiki/Limits

The max building height was increased about the time they finally implemented Havok 4 physics. Used to be 768 Meters, and now it is 4096 Meters.

Teleporting works fine to 4096 Meters, but there are still some issues I believe with high-altitude landmarks? A teleport summons works fine though, and so does a home point set that high.

Also, older scripted teleport methods don't work to that altitude. But the newest generation of scripted teleporters work fine.

Note however that ban lines for people banned explicitly by name still only extend to 768 Meters. So above that height, the only way to ban access is with a scripted security system.

There are no 'recommendations', only actual limits of the system as a whole. This may not be the case everywhere. You can do whatever you want on mainland, but some (not all), estates have covenants forbidding skyboxes/platforms. Something to take into consideration.

There is a point high up where you know longer follow Virtuality Relativities. It's what keeps us here and not there. Avatars will never get into space and we will fall off teh edge of our world.

But you can get to 80,000 meters.

Oh, and you can set landmarks at 4000 meters too.