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Listed by Mitch Varley • Compass New England, LLC

$35,000,000

Est. payment - /mo

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6 Beds

9 Baths

13,451 SqFt

New

518 New Castle AVE Portsmouth, NH 03801

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Alyson Traficante

alyson@alysonsells.com +1(978) 857-0270

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Key Details

Property Type Single Family Home

Sub Type Single Family

Listing Status Active

Purchase Type For Sale

Square Footage 13,451 sqft

Price per Sqft $2,602

MLS Listing ID 5114173

Style Colonial

Bedrooms 6

Full Baths 7

Half Baths 2

Construction Status Existing

Year Built 2001

Annual Tax Amount $162,922

Tax Year 2025

Lot Size 7.700 Acres

Acres 7.7

Property Sub-Type Single Family

Property Description

There are properties that simply cannot be replicated. Privately sited on 7.7 waterfront acres on Portsmouth's coveted Shapleigh Island, 518 New Castle Avenue is a once-in-a-generation New England estate, an extraordinary convergence of scale, privacy, architecture, and waterfront living just moments from the heart of downtown Portsmouth. With 13,450± square feet, this magnificent Shingle Style residence was conceived on a grand scale, pairing timeless coastal architecture with exceptional craftsmanship and sophisticated modern living. Georgian-inspired millwork, stately Tuscan columns, intricate wainscoting, and beautifully proportioned interiors create a residence of remarkable presence, while walls of windows capture sweeping water views and an ever-changing maritime landscape. Across 17 rooms, the estate offers 6 bedrooms, 7 full and 2 half baths, and an impressive collection of formal and informal living spaces equally suited for everyday living and grand-scale entertaining. A newly added balcony overlooking the pool creates an elevated vantage point of the estate's sweeping water views. Beyond the home, manicured grounds descend toward the Piscataqua River, where a private deep-water dock provides direct access to Portsmouth Harbor and the open Atlantic beyond. An attached 3-car garage is complemented by a separate 2-car garage with a finished 1-bedroom, 1-bath guest accommodation above, creating a private and flexible retreat for visitors. Nearly 6,000 square feet of unfinished lower-level space offers exceptional flexibility and storage, while a new roof completed in 2025 represents a significant recent improvement. Yet perhaps the estate's greatest luxury is one that cannot be recreated: complete seclusion across 7.7 waterfront acres while remaining connected to downtown Portsmouth and its cultural, culinary, and coastal lifestyle. 518 New Castle Ave is a landmark NH estate and a rare opportunity to steward one of the region's defining legacy properties.

Location

State NH

County Nh-rockingham

Area Nh-Rockingham

Zoning SRA

Body of Water Piscataqua River

Rooms

Basement Entrance Interior

Basement Interior Stairs, Partially Finished

Interior

Heating Propane, Hot Air, Multi Zone, Radiant

Cooling Central AC, Multi Zone

Exterior

Parking Features Yes

Garage Spaces 5.0

Utilities Available Underground Utilities

Water Access Desc Yes

Roof Type Architectural Shingle

Building

Lot Description Landscaped, Level, Island, Near Country Club, Near Golf Course, Near Shopping, Neighborhood, Near Hospital, Near School(s)

Story 2

Sewer Public

Water Private

Architectural Style Colonial

Construction Status Existing

Others

Special Listing Condition None

Nearby Locations

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Alyson Traficante

Broker Associate

+1(978) 857-0270

518 New Castle AVE Portsmouth, NH 03801

Alyson Traficante

Key Details

Location

Rooms

Interior

Exterior

Building

Others

Nearby Locations

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518 New Castle AVE