Listing by Fortune Christie's International Real EstateMLS® #A12082121
5
Beds
4
Baths
3,085
SQUARE FEET
Single Family Residence
Type
1961
Built
Listing courtesy of
Coldwell Banker Realty
Maureen Jauregui
MLS® #A12071221
Listing information last updated August 26, 2026
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Overview
This single family residence in Key Biscayne has 5 bedrooms and 4 bathrooms across 3,085 square feet, and is listed for sale at $19,900,000 (about $6,451 per square foot). Built in 1961.
Seize a rare opportunity to create a landmark waterfront estate on one of the largest residential lots in Key Biscayne’s exclusive Mashta Island enclave. Spanning an extraordinary 22,140 square feet, this exceptional property offers 138 feet of pristine water frontage and sweeping open water views, providing an unparalleled setting for a world class residence.
Plans by renowned architect, Pablo Corazzini of Vitalini Corazzini Architects, are available to the buyer, offering a thoughtfully conceived vision that takes full advantage of the property’s remarkable scale, premier waterfront setting, and spectacular sunsets. The proposed design creates an extraordinary canvas for sophisticated indoor-outdoor living and entertaining, should the buyer choose to pursue the concept.
With its exceptional lot size, expansive water frontage, and coveted Mashta Island address, this is a truly irreplaceable opportunity to create a legacy estate in one of South Florida’s most prestigious waterfront communities.
Listing history
Listed for sale
Aug 12, 2026 · MIAMI MLS
$19,900,000
Days on market
as of today
24 days
Building & financials
FROM MIAMI MLSThe carrying-cost and structural facts that close or kill a Miami deal — straight from the listing feed.
Annual property tax (2026)
$201,741
Association type
None
Waterfront
Ocean Access, Seawall
Dues, taxes, and association data per MIAMI MLS and public records; flood zone from FEMA NFHL. Verify with the HOA, county, and your insurer during due diligence.
Property details
MLS #A12071221
Price$19,900,000
Size3,085 Square Feet
Bedrooms5
Bathrooms4
Garage2
Year built1961
TypeSingle Family Residence
StatusFor Sale
Price / Square Feet$6,451
Features & amenities
Family Room
First Floor Entry
Has a View
Has Cooling System
Has Garage
Has Heating System
Has Waterfront
Open Parking
Other Equipment/Appliances
Split Bedroom
Location
520 S Mashta Dr, Key Biscayne FL 33149
Estimate your payment
$
Est. monthly payment
—
per month
Principal & interest—
Property tax (est.)—
Down (20%)—
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Listing by Fortune Christie's International Real EstateMLS® #A11838855
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List your rental →Listing data © MIAMI MLS · IDX information deemed reliable but not guaranteed · 24 days on market.
We do not advertise a “free” buyer’s agent; buyer-representation compensation is disclosed in writing. Bitcoin pricing is indicative and updates with the market — not financial, tax, or legal advice. Buyer to independently verify all measurements, assessments, and flood & insurance facts.