520 S Mashta Drive, Key Biscayne, FL 33149

$19,900,000

Virtual Tour

https://www.propertypanorama.com/instaview/mia/A12071221

Conceptual rendering illustrating a potential future residence, customizable at the purchaser’s discretion.

Property Type: Residential Bedrooms: 5 Baths: 4 Square Footage: 4,177 Status: Active

Current Price: $19,900,000 List Date: 8/12/2026 Last Modified: 8/19/2026

Overview

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 ... (Read more)

Listing Details MLS# A12071221

General Property Information

Property Sub Type: Single Family Residence
Bedrooms Total: 5
Bathrooms Total: 4
Bathrooms Full: 4
Building Area Main: 4177
Living Area Main: 3085
Adjusted Area Main: 3578
Year Built: 1961
Garage YN: Yes
Garage Spaces: 2
Covered Spaces: 2
Lot Size Area: 22140
Lot Size Acres: 0.51
Senior Community YN: No
Waterfront YN: Yes
Water Frontage Feet: 138
Stories Total: Yes
Direction Faces: East
Pool Private YN: Yes

Property Features

Flooring: Tile Leasing Permitted Details: Okay To Lease Parking Features: Driveway Property Condition: Resale Appliances: Other Boat and Dock Features: Private Dock Construction Materials: Block Cooling: Central Air Heating: Central Interior Features: Bedroom Layout - Split Levels: One Listing Terms: Cash; Conventional Other Equipment: Other Pool Features: In Ground Possession: Negotiable Roof: Barrel; Spanish Tile Sewer: Public Sewer Special Information: Sold As-Is Water Access: Ocean Access Water Source: Public Water View: Bay; Direct Ocean Waterfront Features: Bayfront; Seawall Showing Requirements: Call Listing Agent Room Types: Family Room Acreage Description: 1/2 To Less Than 1 Acre Lot

Contract Information

Comp Sale YN: No
Original List Price: 19900000
Occupant Type: Call Listing Agent

Location and Legal

Country: United States
County Or Parish: Miami-Dade
County Parish Name: Miami-Dade
Street Number: 520
Street Direction Prefix: S
Street Name: Mashta
Street Suffix: Drive
City Name: Key Biscayne
Municipal Code: 24
State Or Province: FL
Postal Code: 33149
Postal Code +4: 1733
Postal Zip: 33149
Subdivision Name: MASHTA ISLAND A REPLAT OF
Area: 2520
Elementary School: Key Biscayne K-8
Middle Or Junior School: Ponce De Leon
High School: Coral Gables
Parcel Number: 2452050090170
Subdivision Number: 9
Zoning: 2001
Flood Zone: AE

Financial Information

Membership Fee Required YN: No
Tax Annual Amount: 201741
Tax Year: 2026
Tax Legal Description: 5-6 55 42 MASHTA ISLAND A REPLAT OF TRS A & C SELY35FT LOT 16 & ALL LT 17 BLK BLK 3 LOT SIZE 135.000 X 164 OR 15816-1278 1292 1
Estimated Monthly Assoc Recurring Fee: 0

Status Change Information

Major Change Timestamp: 2026-08-12T04:00:00Z
Major Change Type: New Listing
Status Change Date: 2026-08-17

More Information

Entry Information

Entry Level: Yes

Leasing Permitted Details

Leasing Permitted YN: Yes
Okay To Lease: Yes

Boat and Dock Information

Dock: Yes

Storm Protection

Impact Glass: Partial

Price Calculations

Current Price To SqFt: 6450.56

Section Details

Parcel Number MLX: 0170

Originating Details

Originating System Key: 550489621
Originating System ID: M00000151

Office/Member Information

DXORIGMLSID: SEF

Amenities

Other: Yes

Flooring

Tile: Yes

Parking Features

Driveway: Yes

Property Condition

Resale: Yes

Possession

Negotiable: Yes

Sewer

Public Sewer: Yes

Special Information

Sold As-Is: Yes

Heating

Central: Yes

Water Access

Ocean Access: Yes

Water View

Bay: Yes
Direct Ocean: Yes

Appliances

Other: Yes

Construction Materials

Block: Yes

Interior Features

Bedroom Layout - Split: Yes

Levels

One: Yes

Listing Terms

Cash: Yes
Conventional: Yes

Other Equipment

Other: Yes

Pool Features

In Ground: Yes

Roof

Barrel: Yes
Spanish Tile: Yes

Water Source

Public: Yes

Waterfront Features

Bayfront: Yes
Seawall: Yes

Boat and Dock Features

Private Dock: Yes

Cooling

Central Air: Yes

Showing Requirements

Call Listing Agent: Yes

Master Bedroom/Bath

Master Bdrm - Ground: Yes

Pool Size Details

Pool Size (WxL): No

Room Types

Family Room: Yes

Acreage Description

1/2 To Less Than 1 Acre Lot: Yes

Room Information

Room Name
Family Room

Listing Office: Coldwell Banker Realty

Last Updated: August - 19 - 2026

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520 S Mashta Drive, Key Biscayne, FL 33149 (MLS# A12071221)