MASHTA ISLAND A REPLAT OF

520 S Mashta Dr, Key Biscayne FL 33149

5 beds · 4 baths · 3,085 ft²

For Sale · Active Listing

$19,900,000

Est. Payment $105,916/mo

MLS Sheet Video

5

Bedrooms

4

Bathrooms

3,085

Sq. Ft.

1961

Year Built

2

Garage

7

Days on Market

Description

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.

Facts

MLS#
A12071221
Subdivision
MASHTA ISLAND A REPLAT OF
Property Type
Residential
Property Sub Type
Single Family Residence
Year Built
1961
Lot Size
22,140 ft²
Sq. Ft.
3,085 ft²
Sq. Mt.
287 m²
Price per sq. ft.
$6,451/ft²
Price per sq. mt.
$69,338/m²
Stories
Garage
2 spaces
Pool
Days on Market
7 days
Listed
Aug 12, 2026
Last Updated
Aug 19, 2026
Price/Lot Sq.Ft.
$899/ft²

Comparable homes

Same ZIP, similar price + bedrooms.

Market insights for Key Biscayne

Live MLS-derived activity. Forecast is a conservative rule-of-thumb estimate — not a guarantee.

Sellers market

August 2026

100/100
Buyers marketSellers market

50

Median days to sold

+4.5%

1-year price forecast (est.)

Price & tax history

From the live MIAMI MLS feed. Older history requires the ListingHistory resource (not yet enabled).

8/12/2026Listed for sale$19,900,000

History reflects fields present on the live MLS record. Full multi-year history requires the MIAMI ListingHistory resource (not yet enabled).

Location

520 S Mashta Dr, Key Biscayne FL 33149Directions

Estimated Monthly Payment

$122,649/mo

Principal & Interest

$105,916

Property Tax

$16,583

Insurance

$150

HOA

$0

20% ($3,980,000)
7.00%
30 years
1.00% (FL avg ~1.0%)
$0/mo
$150/mo

Estimates only. Actual payment depends on credit, lender, insurance carrier, and FL/Miami-Dade specifics. Contact Rangely for a precise quote.

Rangely Adames

Rangely Adames

Sales Associate | Sunland Group

Hablo Español

The data relating to real estate for sale on this website comes in part from the Southeast Florida Multiple Listing Service. MLS Data is deemed reliable, but is not guaranteed accurate by MIAMI REALTORS®.

Accuracy of listing information is not guaranteed. Listing information is provided for personal consumer, non-commercial use, solely to identify potential properties for potential purchase. All other use is strictly prohibited and may be a violation of federal and state law.

Copyright Southeast Florida MLS a/k/a SEFMLS © 2026.

Updated 10 hours ago

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