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Single Family Residence
$8,000,000$7,663 / sqft
544 Warren Ln, Key Biscayne FL 33149
Listed
6
Bedrooms
6
Bathrooms
1,044 sqft
Interior
2026
Year built
None
HOA
Single Family Residence
Type
About this home
New construction, this extraordinary custom Cape Dutch residence is a masterwork of timeless design, brought to life by Duncan and Heuser Design and Development, with interiors curated by James Duncan. Every detail, from the graceful gabled facade to the refined finishes within, reflects a rare devotion to craftsmanship and enduring elegance. Offering six generously proportioned bedrooms and six and a half beautifully appointed bathrooms, this home balances gracious scale with warm, livable comfort. Soaring ceilings, thoughtfully placed windows, and an effortless flow between rooms create a sense of light and openness throughout, while curated materials and bespoke millwork lend a distinctly luxurious character to every space. This is more than a house; it is a legacy residence, designed to be lived in beautifully for generations. A truly rare offering for the discerning buyer seeking timeless architecture, exceptional interiors, and uncompromising quality throughout.
Features
- First Floor Entry
- Vaulted Ceiling(s)
- Walk-In Closet(s)
- Other
- Built-In Grill
- Garden
- Pool
Location
Approximate — shows the building, not the unit. Open in maps
Run the numbers
We fill in the price and the building's HOA dues. That leaves tax, insurance and maintenance — they depend on your exemptions, your insurer and the unit, so we don't guess them. Rent starts from what comparable units are asking nearby. Vacancy and the loan terms below start at common defaults; change them.
Median asking rent for 6-bed rentals in Key Biscayne, from 5 active listings; the middle half ask $21,500–$75,000.That is what landlords ask, not what units let for — edit it if you know better.
Our default, not a market figure
From the listing
Depends on assessed value & exemptions
Varies widely by building
Repairs, turnover, management
Cap rate
Cash-on-cash
Monthly cash flow
Net operating income
Enter property tax, insurance, maintenance to see the returns. A cap rate calculated without every cost overstates the deal — often by half — so we don't show a partial one.
Illustration only — not a loan offer, quote, or investment advice. We are not a lender and neither offer nor arrange financing. The loan fields start at 20% down over 30 years at 6.5% (rates as of July 2026); that is a nominal rate for illustration, not an APR, and your actual terms will differ. Cap rate is unlevered; cash-on-cash counts the down payment as invested capital and excludes closing costs.
Listing data from the MIAMI Association of REALTORS® (MIAMIRE) IDX program. Information deemed reliable but not guaranteed. Demo data shown for layout purposes.