House in Key Biscayne, FL 33149Mashta Island, 520 S Mashta Dr
Open Wed, 12:00 PM–2:00 PM






$18,500,000
$2M5
Beds4
Baths3,085
SqFt$5,997
$/SqFtUltra Luxury HouseProperty Type
1961Year Built
$5,997/SqFtPrice per sq ft
2 carsParking Spaces
Bay,OceanView
YesWaterfront
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.
Open House
Wednesday, November 4
12:00 PM – 2:00 PM
Listing Courtesy Of: Coldwell Banker Realty
Local Realty Services Provided By: Best of Luxury Realty
On Site: 72 DaysUpdated: 1 Days agoPage Views: 0
Features
MLS Number: A12071221
Bedrooms
- Bedrooms: 5
Bathrooms
- Bathrooms: 4
- Half Bathrooms: No info
Exterior and Lot Features
- Exterior Features: SecurityHighImpactDoors
- View: Bay,Ocean
Interior, Heating and Cooling
- Interior Features: BedroomOnMainLevel, FirstFloorEntry, SplitBedrooms
- Equipment / Appliances: Other
- Heating Description: Central
- Cooling Description: CentralAir
Building and Construction
- Floor Description: Tile
- Year Built: 1961
- Year Built Description: Resale
- Style: OneStory
Waterfront and Water Access
- Waterfront Frontage: Yes
School Information
- Elementary School: Keybiscayne
- Middle School: Ponce De Leon
- Senior High School: Coral Gables
Other Property Info
- Garage: 2
- Listing Date: 2026-08-17T17:00:09.000-00:00
- Directions: East
Taxes, Fees & More
- Taxes: 201741
- Parking Description: Driveway
Apples-to-Apples Comparables
Price History
Current
$18.5M
High
$19.9M
Low
$18.5M
Total Change
-7%Date
Event
Price
Change
Price Per
10/23/2026
Price Reduced
$18.5M
-7.04%$5,997 ft2
$64,549 m2
08/14/2026
Listed
$19.9M
$6,451 ft2
$69,434 m2
10/23/2026
$18.5M
Event
Price Reduced
Change
-7.04%Price Per
$5,997 ft2
$64,549 m2
08/14/2026
$19.9M
Event
Listed
Price Per
$6,451 ft2
$69,434 m2
Price per square foot and days on website are not provided values and are calculated by Subdivisions.
Listed by Maureen Jauregui • Coldwell Banker Realty • Buyer Agency Compensation .
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Community Snapshot
4 – 5 BR
Bedrooms
$6.4M – $19.9M
Price Tier
2,255 - 10,820
SqFt Range
1972
Year Build
1
Total Floors
71
Total Units
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