You’ve probably seen the tall gates while driving down River Road in Potomac. Maybe you’ve wondered what’s actually behind those thick, manicured hedges. Honestly, if you’re looking for the largest house in Maryland, you’re not just looking for a home—you’re looking for a small village wrapped in limestone.
That title belongs to Norton Manor.
It’s an absolute beast of a residence. Owned by IT entrepreneur Frank Islam and his wife, Debbie Driesman, this estate is basically the gold standard for "over the top" in the DMV area. We are talking about a property that spans roughly 47,000 square feet of finished living space. To put that in perspective, the average American home is about 2,500 square feet. You could fit nearly 19 average houses inside this one Maryland footprint.
What’s Actually Inside Norton Manor?
Most people assume these mega-mansions are just empty hallways and dusty ballrooms. Not here. Norton Manor was designed to be a "convening space." Because Islam and Driesman are major fixtures in the political and philanthropic world, the house functions half as a private sanctuary and half as a diplomatic hub.
Here is the breakdown of the insanity:
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- 16 bedrooms and 22 bathrooms. You could host a mid-sized wedding party and everyone would still have their own shower.
- The Presidential Touch: The office contains a replica of the Resolute Desk—the same one used in the Oval Office.
- A "Sound of Music" Gazebo: There is a literal gazebo on the grounds inspired by the movie. No, really.
- The Reflection Pool: Inspired by the Rashtrapati Bhavan in New Delhi, the front driveway ends at a massive reflecting pool that makes the entrance feel like a monument.
The grounds are just as wild as the interior. We’re talking about 10 acres that feature a 2,000-square-foot koi pond, formal knot gardens modeled after Henry VIII’s Hampton Court Palace, and a 450-foot man-made stream. Maintaining just the gardens and security reportedly costs around $1 million a year.
It’s Not Just About the Square Footage
While Norton Manor holds the crown for total complex size (including its massive guest house), there’s always a bit of a "size war" in Montgomery County. For a long time, people pointed to Haveli, a 35,000-square-foot mansion built by cosmetics mogul Rashid Chaudhary. It gained fame for having the largest chandelier ever hung in a private residence.
Then there’s the "French Chateau" at 11900 River Road. That property recently hit the market for nearly $25 million. While the main house is "only" about 25,000 square feet, the total structural area across the estate's multiple buildings pushes over 40,000 square feet.
Why Potomac is the Epicenter
If you’re searching for the largest house in Maryland, you aren't going to find it in Baltimore or Annapolis. You find it in the 20854 zip code.
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Why? It’s the "Goldilocks" zone. It is far enough from D.C. to have massive 10-plus acre lots, but close enough for lobbyists, tech CEOs, and diplomats to commute. The zoning laws in this specific pocket of Potomac allow for these sprawling footprints that would be illegal in more densely packed suburbs.
Kinda crazy, right?
But there’s a nuance here most people miss. Size in 2026 isn't just about bragging rights anymore. Experts like those at Sotheby’s and Redfin have noticed a shift. The newest "mega" builds in Maryland are focusing more on "wellness wings" and "multigenerational suites" rather than just adding more bedrooms.
The Reality of Owning a Mega-Mansion
Living in the largest house in Maryland sounds like a dream, but the logistics are a nightmare. Most of these owners have full-time staff just to handle the HVAC systems. When you have 265 windows (like at Haveli), you don't just "clean the windows." You hire a specialized crew that stays for a week.
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Also, the tax bills.
The annual property taxes on a place like Norton Manor or the River Road estates can easily exceed $200,000. That’s enough to buy a small house in many parts of the country—every single year—just in taxes.
Misconceptions About These Homes
- They are always for sale: Actually, once someone builds a 40,000-square-foot custom home, they usually stay. These are "legacy" properties.
- They are empty: While some are "investment" shells, the big ones in Maryland (like Islam's) are used constantly for fundraisers and events.
- The square footage is all "living" space: A huge chunk of that 47,000 square feet is often taken up by massive garages (some hold 14+ cars), indoor pools, and mechanical rooms.
Your Next Steps if You're Mansion Hunting (or Just Dreaming)
If you're actually in the market for Maryland's elite real estate, or if you're just a fan of architectural voyeurism, you should keep an eye on Montgomery County property records. They are public, and that’s where the "official" square footage is logged.
- Check Zillow’s "Luxury" filter for Potomac and Bethesda. You’ll often see these 20,000+ square footers pop up under "off-market" or "coming soon."
- Follow local architects like John Ike or Horizon Builders. They are the ones actually drafting these massive limestone footprints.
- Drive down River Road or Bradley Blvd. You won't see much past the gates, but the scale of the entrance tells you everything you need to know about what's hiding in the woods.
Maryland’s luxury market is currently in what experts call the "Great Housing Reset." Prices are stabilizing, and while the "average" house is getting smaller, the "mega-mansion" class is only getting more complex and tech-heavy. Whether it’s Norton Manor or the next billionaire’s project, the largest house in Maryland remains a testament to the sheer scale of the American Dream—at least for those with a few extra million in the bank.