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520 S Mashta Dr, Key Biscayne FL 33149

House For Sale
$19,900,000

BTC: 310.93750000

ETH: 10,459.15149477

New
Waterfront
5 bds
4 ba
3,085 sqft

Overview

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.

Location

Florida • Key Biscayne • 33149 • House • For Sale • Waterfront

Details

Type:
Residential
Parking:
Driveway
Year Built:
1961
Lot:
22140 Square Feet
Heating:
Central
Price/sqft:
$6,451
Cooling:
Central Air
HOA:
No Data

Valuation

Our model vs. what's actually selling nearby.
Estimate
$1,722,450
$1.1M – $15.7M
Confidence Low
List vs. estimate
$18.2M above estimate
List $19,900,000 · +1055.3%
Our model says this listing is priced above recent comparable activity. Room to negotiate.
Price per sq ft
$6,450
+230.9% vs. city median $1,949
Based on
12 MLS comparables
+ 12 public-records sales within 0.5 mi
Median actual sale: $3.3M
Median of recent comparable listings. Sold comps use closing price, active listings use list price.

Highlights

Annual tax
$201,741
2026
Pool
In Ground
View
Bay, Direct Ocean
Waterfront
Ocean Access, Seawall
Garage
2 car garage
All facts and features

  • Flooring

    • Tile

    Heating

    • Central

    Cooling

    • Central Air

    Appliances

    • Other Equipment/Appliances

    Other interior features

    • First Floor Entry

    • Split Bedroom

    • Family Room

    Bedrooms and bathrooms

    • Bedrooms: 5

    • Full bathrooms: 4

  • Parking

    • Driveway

    Lot

    • Lot: 22140 Square Feet

    Other Property Information

    • Parcel Number: 24-52-05-009-0170

    • Zoning: 2001

  • Type and style

    • Property Type: Residential

    • Property Sub Type: Single Family Residence

  • Other financial information

    • Annual tax amount: $201,741

  • Source details

    • MLS ID: A12071221

    Other facts

    • Construction Materials: Concrete Block Construction

    • Lot Features: 1/2 To Less Than 3/4 Acre Lot

    • Pool Features: In Ground

    • Direction Faces: East

    • Architectural Style: Attached / One Story

    • Waterfront: Yes

    • Garage Spaces: 2

    • Garage: Yes

    • Living Area: 3085

    • Water Source: Municipal Water

    • Subdivision Name: MASHTA ISLAND A REPLAT OF

Private inquiry
Talk to the advisor on this listing.
Floor plans, HOA docs, off-market comparables, scheduling a private showing — one message, direct to the local specialist.

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Market around this address

Live counts in the same area.
View all
This zip
33149
143
median $2.5M
Active
Same city
Key Biscayne
143
median $2.5M
Active
Same type
House
37
median $7.5M
Active
Similar price
$13.9M – $25.9M
10
median $18.7M
Active

The multiple listing information is provided by the Miami Association of REALTORS® from a copyrighted compilation of listings. The compilation of listings and each individual listing are ©2026-present Miami Association of REALTORS®. All Rights Reserved. The information provided is for consumers' personal, noncommercial use and may not be used for any purpose other than to identify prospective properties consumers may be interested in purchasing. All properties are subject to prior sale or withdrawal. All information provided is deemed reliable but is not guaranteed accurate, and should be independently verified. Listing courtesy of: Coldwell Banker Realty