By John McDevitt

PHILADELPHIA (CBS) — An “ultra lux,” $150-million condominium high-rise building is planned for historic Philadelphia, on the edge of Independence Mall.

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And because of its proximity to Independence Hall and the Liberty Bell, the National Park Service is getting involved in the project.

The planned 26-story, glass “needle” tower at 5th and Walnut Streets will be marketed to the ultra-high-end buyer.   Its 40 residences range in size from 2,500 square feet to about 8,400 square feet for each of the  two double-story penthouses near the top.

An automated garage would be able to retrieve your vehicle in 90 seconds.

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(Artist's rendering of 500 Walnut Street project.)

(Artist’s rendering of 500 Walnut Street project.)

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Cecil Baker, the architect of 500 Walnut, says the National Park Service has been involved in the project because they don’t want the tower too close to Independence Hall at the Liberty Bell pavilion, diminishing the presentation of those historic tourist attractions.

“They do not want the sky blocked off on the site,” Parker says.  “That has meant that this building is pulled back from Walnut Street, and it’s severely angled to the sky.  So, by its nature, it’s a pretty aggressive shape.”

He says the design process is still underway but guesses the residences will cost more than $450 per square foot.

Construction is planned to start in spring of 2015, and it’s expected to take two years to complete.

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