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 Provided Courtesy of Coldwell Banker Realty at 305-361-5722
Property Details
Price:
$18,500,000
MLS #:
A12071221
Status:
Active
Beds:
5
Baths:
4
Type:
Single Family
Subtype:
Single Family Residence
Subdivision:
MASHTA ISLAND A REPLAT OF
Neighborhood:
2520
Listed Date:
Aug 11, 2026
Finished Sq Ft:
3,085
Total Sq Ft:
4,177
Lot Size:
964,418,400 sqft / 0.51 acres (approx)
Year Built:
1961
See this Listing
Schools
Elementary School:
Key Biscayne K-8
Middle School:
Ponce De Leon
High School:
Coral Gables
Interior
Appliances
Other
Bathrooms
4 Full Bathrooms
Cooling
Central Air
Flooring
Tile
Heating
Central
Interior Features
Bedroom Layout – Split
Levels
One
Exterior
Association Amenities
Other
Construction Materials
Block
Covered Spaces
2
Direction Faces
East
Garage Spaces
2
Parking Features
Driveway
Roof
Barrel, Spanish Tile
View
Direct Ocean, Bay
Waterfront Features
Ocean Access, Bay, Seawall
Financial
Tax Year
2026
Taxes
$201,741
Map
Community
- Address520 S Mashta Drive Key Biscayne FL
- SubdivisionMASHTA ISLAND A REPLAT OF
- CityKey Biscayne
- CountyMiami-Dade
- Zip Code33149
Subdivisions in Key Biscayne
- 155 SUNRISE CONDO
- 32 54 42 & 5 55 42
- 325 FERNWOOD ROAD CONDO
- 544-548 FERNWOOD CONDO
- 596 Fernwood
- BAHAMA HOUSE SOUTH CONDO
- BAHIA MAR CONDO OF KEY BI
- BISCAYNE KEY ESTATES
- BISCAYNE KEY ESTATES SUB
- BLUE PELICAN CONDO
- CAPE FLA CLUB CONDO CLUST
- CAPE FLA SUB SEC 2
- CAPE FLORIDA CLUB CONDO
- CAPE FLORIDA CLUB CONDO P
- CAPE FLORIDA SUB SEC 1
- CAPE FLORIDA SUB SEC 3
- CASA DEL MAR CONDO
- CAY POLYNESIA CONDO
- CLUB TOWER ONE CONDO
- CLUB TOWER THREE CONDO
- CLUB TOWER TWO CONDO
- Commodore Club East
- COMMODORE CLUB SOUTH COND
- COMMODORE CLUB WEST CONDO
- CRANDON TOWER CONDO
- G B RESORT CONDO HOTEL
- G B VILLAS
- GALEN BREAKERS CONDO
- GALEN BREAKERS CONDOMINIU
- GALEN DRIVE CONDO APTS
- GALEN DRIVE WEST CONDOMINIUM
- GARDENS OF KEY BISCAYNE
- GDNS OF KEY BISC – ALHAMB
- GDNS OF KEY BISC-ALHAMBRA
- GOVERNORS LODGE ASSOC CON
- GRAND BAY RESIDENCES COND
- GRAND BAY TOWER CONDO
- GRAND KEY ESTATES
- GRAPETREE TOWNHOUSE CONDO
- HOLIDAY COLONY
- HURRICANE COVE
- INDIES CONDO
- ISLAND BREAKERS CONDO
- ISLAND HOUSE
- ISLAND HOUSE APT INC – CO
- KEY BISC AMBASSADOR CONDO
- Key Biscayne
- KEY BISCAYNE COMMODORE CL
- KEY BISCAYNE COMMODORE CLUB
- KEY BISCAYNE VI CONDO
- KEY BISCAYNES COMMODORE C
- KEY COLONY
- KEY COLONY NO 1
- KEY COLONY NO 2 CONDO
- KEY COLONY NO 4 CONDO
- KEY ISLANDER CONDO
- Key Islander Condominium
- LAKE TOWER CONDO
- LAKE VILLA ONE CONDO
- LAKE VILLA THREE CONDO
- LAKE VILLA TWO CONDO
- LE PHARE KEY BISCAYNE CON
- MAR-AZUL CONDO
- MASHTA ISLAND
- MASHTA ISLAND A REPLAT OF
- MASHTA POINT SUB
- MATHESON ESTATES
- OCEAN LANE PLAZA CONDO
- OCEAN TOWER ONE CONDO
- OCEAN TOWER TWO CONDO
- OCEAN VILLAGE CONDO
- OCEANA KEY BISCAYNE CONDO
- RESORT VILLA ONE CONDO
- RESORT VILLA TWO CONDO
- SANDS OF KEY BISCAYNE CON
- SMUGGLERS COVE
- SOLIMAR CONDO OF KEY BISC
- SUNRISE CLUB CONDO
- SUNRISE MANOR CONDO
- THE EMERALD BAY
- THE EMERALDBAY @ KEY COLO
- THE EMERALDBAY @ KEY COLON
- THE PALMS OF KEY BISCAYNE
- THE PYRAMIDS @ KEY BISCAY
- TOWERS OF KEY BISCAYNE CO
- TROPICAL ISLE HOMES RESUB
- TROPICAL ISLE HOMES SUB
- TROPICAL ISLE HOMES SUB 1
- TROPICAL ISLE HOMES SUB 2N
- TROPICAL ISLE HOMES SUB 3
- TROPICAL ISLE HOMES SUB 4
- TROPICAL ISLES HOMES
Market Summary
Current real estate data for Single Family in Key Biscayne as of Nov 12, 2026
44
Single Family Listed
150
Avg DOM
2,746
Avg $ / SqFt
$14,623,659
Avg List Price
Property Summary
- Located in the MASHTA ISLAND A REPLAT OF subdivision, 520 S Mashta Drive Key Biscayne FL is a Single Family for sale in Key Biscayne, FL, 33149. It is listed for $18,500,000 and features 5 beds, 4 baths, and has approximately 3,085 square feet of living space, and was originally constructed in 1961. The current price per square foot is $5,997. The average price per square foot for Single Family listings in Key Biscayne is $2,746. The average listing price for Single Family in Key Biscayne is $14,623,659.
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520 S Mashta Drive
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