[Mikec526]

I want to build a long arbor in my backyard, and I want to build it out of metal. What type of metal should I use to make it last? Thanks for the help.

[cj737]

If you are leaving unpainted/uncoated, then Corten, stainless or aluminum.
If you going to paint/powder coat it, then mild steel tubing works perfectly well.

Many arbor designs have arched segments for which you will need a ring-roller to prevent the tube from collapsing.

Or you can make it from wood and avoid all this mess

[manac]

Does anyone have an idea how well 6061 will do in contact with the ground?
Fairly wet part of the country.