What We've Done

2424 Studios

90-unit commercial office building with tenants ranging from physicians to artists.

Woody's Nightclub

Multi-level club in Center City, Philadelphia that was completely rehabbed.

J Street Lofts

64-unit gated apartment complex located in Northwest Philadelphia.

365 Live Fitness Loft

Fitness loft and boxing club located on 5th Street near Fishtown.

1849 E Venango

Welcome to The Chocolate Factory, our most recently constructed living complex.

139 Jefferson

New build with a modern design located minutes from the heart of Fishtown.

Apartment & Office Rentals

GM Holdings, LLC is a property management company dedicated to commercial and residential realty in Fishtown, Harrowgate, Kensington, Northern Liberties & Port Richmond, Philadelphia. Click here to see all available properties!

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Why Work With Stronghold?

We Invest In The Community

We understand the importance of stabilizing local neighborhoods that are negatively affected by neglected properties.

We Stand Out

We believe in high-quality developing with unique layouts and individual touches. We want to help make your vision come true, however big or small.

We Are Affordable

We understand the value of a dollar. That's why we over complex development and construction at a modest price.

We Care About Our Clients

We are happy to collaborate with investors and the community to ensure that everyone is satisfied. 


Philadelphia Magazine


New Construction Factory-Style Loft Apartments Now Available in Harrowgate

The loft-apartment aesthetic remains popular with a large swath of city-lovers. These fans of industrial chic have flocked to the converted factories and warehouses found in neighborhoods all over the city, and builders have responded by scooping up old industrial buildings further and further afield from the neighborhoods like Callowhill and Northern Liberties where such buildings abound.

Stronghold Development, the construction arm of Manosis’ real estate enterprise, installed the framework for a dropped tile ceiling in each kitchen but omitted the ceiling tile, except where lights were placed. “We think it’s a cool aesthetic,” says Anthony Castaneda of Keller Williams Philadelphia, who is part of the team that markets this development.

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Philadelphia Magazine


Apartment Week: J Street Lofts

Not thinking of Harrowgate as a place to live yet? The developer of this stylish former factory near Tioga station wants to change your mind.

As of now, the wave of reinvestment, redevelopment and revitalization that’s transformed large swaths of North and South Philadelphia has yet to leap over the huge freight railroad embankment that crosses eastern North Philadelphia on its way to the massive former Reading Railroad pier complex in Port Richmond.

Kensington developer George Manosis has just placed a huge bet that it will, and soon. In fact, you could call his J Street Lofts complex, a mere block from the Tioga El stop in Harrowgate, the bleeding edge of that wave.

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Old School Getting Converted in Harrowgate

Harrowgate is a neighborhood surrounding the Tioga El Station that abuts the big box commercial strip of Aramingo Avenue. Artisans have begun to move to the neighborhood and set up shop in converted warehouses nearby. Supporting amenities are beginning to sprout in the area.

Many people think that development pressure from East Kensington may jump right to Harrowgate and skip the area between Somerset and Allegheny because of that neighborhood’s opioid epidemic. The belief is that Harrowgate will see large-scale development before northeast Kensington, even though it is farther away geographically from Center City and gentrified neighborhoods such as Fishtown.

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