By Jan Carabeo

PHILADELPHIA (CBS) — From the ground — it’s imperceptible.

To find the PECO Green Roof, you have to go eight stories up.

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From the air, its patchwork of color and texture is revealed.

It was installed in 2009, atop PECO’s headquarters at 23rd and Market Streets in Center City.

This 45,000 square foot secret garden is one of Philly’s first green roofs and still one of the largest of its kind in the entire state.

It provides more than just spectacular views of Philadelphia.

The PECO Green Roof captures more than 70 percent of rainwater that falls during the growing season: an estimated 1.6 million gallons a year.

“They really help capture that storm water before it releases it into the storm water system,” said PHS publications manager Sean Cooper. “It also helps cleanse the water and reduces some of the toxins from getting into the water system.”

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The plantings also help keep summer temps on the roof up to 80 degrees cooler than a conventional roof, reducing energy costs.

The Pennsylvania Horticultural Society maintains the garden and provides tours.

It’s a beautiful look at sustainability is meant to awe and inspire.

“We hope that as more people learn about it, they become inspired to bring green roofs to their own businesses or residences,” said Cooper.

PHS provides tours to well over 600 people a year.

There’s a tour every month.

If you’re interested in your own green roof, experts say do your research. You need to have a structural engineer check it out first.

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For more information on the PECO Green Roof, click here.