518 New Castle Avenue, Portsmouth, NH 03801

Portsmouth
Local realty services provided by:Better Homes and Gardens Real Estate The Masiello Group
518 New Castle Avenue,Portsmouth, NH 03801
$35,000,000
  • 6 Beds
  • 9 Baths
  • 13,451 sq. ft.
  • Single family
  • Active
Listed by: mitch varley
Office: compass new england, llc.978-248-8081
MLS#:5114173
Source:PrimeMLS

Price summary

  • Price:$35,000,000
  • Price per sq. ft.:$1,848.04

About this home

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...

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Home facts

  • Year built:2001
  • Listing ID #:5114173
  • Added:7 day(s) ago
  • Updated:October 22, 2026 at 11:17 AM

Rooms and interior

  • Bedrooms:6
  • Total bathrooms:9
  • Full bathrooms:7
  • Rooms Total:17
  • Basement Description:Interior, Partially Finished
  • Living area:13,451 sq. ft.

Heating and cooling

  • Cooling:Central AC, Multi-zone
  • Heating:Hot Air, Multi Zone, Radiant

Structure and exterior

  • Year built:2001
  • Building area:13,451 sq. ft.
  • Lot area:7.7 Acres
  • Levels:2 Story

Utilities

  • Sewer:Public Available

Finances and disclosures

  • Price:$35,000,000
  • Price per sq. ft.:$1,848.04
  • Tax amount:$162,922 (2025)

Features and amenities

  • Amenities:Circuit Breaker(s), Generator

Parking

  • Parking description:Circular Driveway, Paved Driveway
  • Garage spaces:5
MLS LogoCopyright 2026 Prime MLS, Inc. All rights reserved. This information is deemed reliable, but not guaranteed. The data relating to real estate displayed on this Site comes in part from the IDX Program of Prime MLS. The information being 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. Data last updated October 22, 2026

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