The Waste Water Treatment plant on Hayden and McDonald contains parks and public areas around it. The building is done in a modern style with rusted metal, rocks in rusted mesh and blood red canvas sails for shade.

You wouldn't know it is a waste water treatment plant other than a back entrance has card access and a warning that only authorized personnel are allowed in. Immediately infront of the facility is a water feature and dog parks. There is a shaded amplitheatre of sorts behind the structure and then it blends into baseball parks.

It is possible that disguising it in the modern structure was a requirement or a means to fend of any NIMBY attacks so that it could go through council. It is quite a stunning building and well integrated into the surrounding public space. (more)
Phoenix has a strong modernist and contemporary streak to it. Most of the public spaces have extra care and attention payed to little details such as making things look good/arty. Architecturally rusted metal has become popular in Phoenix.

McDowell Library from my photostream

It is pretty simple. Metal is put up and left to rust. For the terminally impatient pre-rusted metal can be bought for great cost. It comes through in a wonderful orange color though I am yet to convinced that it isn't treated to make it oxidise (rust) in a certain way. (more)
Via Arquitectura Akinetia, the Tattoo house in Fitzroy.

These houses always look wonderful. The tree on the glass looks magic during the day and night. But they are out of reach of the average home owner for the most part. Modernizing a house is exorbitantly expensive. (reply)
Cam Riley: South Sea Republic. Freedom, liberty, equity and an Australian Republic.