Want to build a wide (6.2m) swing set/playset without support.

[vandmo]

Is it possible to do this with treated wood or is a steel beam required?
Has anyone done anything similar?
The idea is to hang swings and similar items, while still having the lawn free underneath.
I want it to be quite high, maybe 2.5m. The back part could have support downwards.
Has anyone done anything similar?

 

[Du och 19till]

A telephone pole holds a couple of swings. Now it's getting harder to find.