Really, what is the point of even having a penthouse if you have to live with someone else's design choices? These three top-shelf, top-floor properties offer well-heeled buyers the opportunity to get exactly what they want. Because they're buying a shell (which is called a "raw space" in polite conversation).

1414 S. Penn Square, Unit PHII 
$14,000,000 
Monthly taxes: Lucky for you, this property includes a tax abatement. Otherwise, taxes would be $15,050. 
Tell me all about it: Have you ever wondered what it would be like to tug on Billy Penn's coattails? This 47th-floor penthouse may be the closest you can get to living out your dream. The space is 9,515 square feet and can be made into whatever your heart desires. The Ritz amenities include Bentley and Escalade chauffer service, as well as a residents park with waterfall and a state-of-the-art fitness center.

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The penthouse view of Philadelphia.
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The penthouse view of Philadelphia.

20 S. Letitia St., Unit 5B & 6A 
$1,750,000 
 Monthly taxes: $1,881 (tax abatement in place) 
Tell me all about it: At 3,600 square feet, this Waterbridge Condo penthouse was designed by Harman Deutsch Architecture. It is the result of combining two separate units and includes some finishes (kitchen cabinetry and lighting are in place) but room for customization. The property also features two separate decks (one of which offers panoramic skyline views from the roof).

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130 S. 18th St., #3202 
$15,000,000 
Monthly taxes: $16,125 
Tell me all about it: This 10 Rittenhouse Square penthouse offers 9,131 square feet and includes four sides of floor-to-ceiling windows. If you'd like to be in the rarefied position of looking down (literally) on Rittenhouse Square, this is your opportunity. The building includes concierge services like Mercedes chauffeur service and a private piano room. The home also comes with four (!) parking spaces.

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