by RH Advisors

See Home Value
$2,799,000
● House - Off Market

317 Old Mill Road

Smithtown, NY 11780
bedrooms
4 Beds
bathrooms
4 Baths, 1 Half Bath
square feet
4,250 Ft²
$17,168
Est. Monthly
0.76%
Cap Rate

About This Property

Welcome to "The Hill Valley House," where timeless design and modern luxury come together in perfect harmony. Completed in 2023 with no expense spared, this one-of-a-kind custom estate sits on 2.66 acres of lush, private grounds and offers an extraordinary blend of timeless design and cutting-edge innovation.

Step inside to experience an ambiance of sophistication and comfort, with soaring 10' ceilings throughout, high-end custom treatments, and impeccable finishes. The grand great room is anchored by a stunning dual-sided gas stone fireplace and flows seamlessly into the heart of the home-a spectacular, state-of-the-art gourmet kitchen. Designed for both beauty and function, this culinary showpiece features rich custom wood cabinetry, sleek quartzite countertops with a dramatic waterfall edge, and a large center island with ample seating-perfect for casual dining or elegant entertaining. The kitchen is fully outfitted with top-tier stainless steel appliances, including a professional-grade six-burner gas stove, wine fridge, and an inviting dinette area that overlooks the tranquil backyard.

The first-floor primary suite is a true sanctuary, boasting walls of glass that invite nature in and a spa-inspired ensuite with exquisite tilework, a soaking tub, walk-in shower, custom wood double vanity, and a spacious walk-in closet. A private first-floor office adds convenience and flexibility. Upstairs, three additional bedrooms each feature their own ensuite baths, including one with a private rooftop deck. A second-floor entertainment area with built in speakers and walk-in storage room or office complete the upper level.

One of the crown jewels of "The Hill Valley House" is the screened-in porch-a luxurious outdoor haven designed for year-round enjoyment. Featuring double French doors, a dramatic dual stone gas fireplace, built-in infrared heaters, and a refined dining area, this exceptional space merges indoor elegance with outdoor serenity.

The finished basement includes a dedicated home gym and a vast unfinished area with endless potential-ideal for a media room, wine cellar, or additional living space tailored to your lifestyle.

Adding to the home's long list of luxuries are a state-of-the-art solar panel system, whole-house water purification, advanced backup power system, smart home technologies, as well as an oversized three-car garage.

Outside, your personal resort awaits-with a heated 19'x36' saltwater in-ground pool, cozy fire pit, and expansive patios-perfect for entertaining or peaceful relaxation.

The Hill Valley House offers a lifestyle that feels like a permanent vacation-set on lush, resort-like grounds, yet just minutes from Long Island Sound beaches, local marinas, restaurants, charming town shops, and Stony Brook University.

Truly, no detail was overlooked in the creation of this exceptional home. From its superior construction to its thoughtfully curated finishes, this is more than a home-it's a lifestyle. Make this dream property yours today.
Unit Size
4,250 Ft²
Days on Market
100 days
Land Size
2.66 acres
Price per sqft
$659
Property Type
House
Property Taxes
$3,424
HOA Dues
-
Year Built
2023

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Last updated: 2 years ago (OneKey MLS #KEY878416)

Price History

Date / Event Date Event Price
Sep 24, 2025 Sold
Sold
Jun 26, 2025 In contract -
In contract
Jun 16, 2025 Listed by Daniel Gale Sothebys Intl Rlty $2,799,000
Listed by Daniel Gale Sothebys Intl Rlty
Oct 22, 2020 Sold
Sold

Property Highlights

Garage
Air Conditioning
Fireplace

Building Info

Overview

    General

  • Year Built: 2023
  • Effective Year Built: 2023
  • Bedroom Count: 4
  • Bathroom Count: 5
  • Full Bathrooms: 4
  • Partial Bathrooms: 5
  • Building Condition: 6
  • Building Quality: 7
  • Construction Type: 0
  • Building Style: 5
  • Exterior Walls Type: 17
  • Interior Walls Type: 0
  • Roof Shape Type: 0
  • Roof Cover Type: 0
  • Floor Count: 200
  • Floor Cover: 0
  • Basement Type: 2
  • Basement Area: 0
  • Garage Type: 1
  • Garage Square Area: 956
  • Parking Space Count: 4
  • Patio Type: 0
  • Porch Type: 6
  • Pool Type: 10

    Dimensions

  • Lot Size Square Feet: 115,870
  • Total Building Area: 4,247
  • Building Area: 4,247
  • Building Area Measurement: L

    Heating and Cooling

  • Fireplace Count: 1
  • Air Conditioning: 1
  • Heating: 3
  • Heated Square Feet: 4,247
  • Heating Fuel Type: 3

    Utilities

  • Sewer System: 0
  • Water Service: 0

Building

  • Building Type: 0
  • Property Class: R
  • Land Acres: 0000002660
  • Standard Land Use Code: 1001
  • County Land Use Code: 210
  • Legal Description 1: 12.-1-4.4 OLD MILL SLOPES LOT 4 *6974

Neighborhood

  • School District Name: Smithtown Central School District
  • School Tax School District: SMITHTOWN
  • Census Tract: 134909

Geography

  • District: 0802-0
  • Section: 12.00
  • Parcel: 0802-012.00-01.00-004.004
  • Block: 1
  • Lot: 4.004
  • Municipality: SMITHTOWN
  • Latitude: 40.886
  • Longitude: -73.1862

    Address

  • Full Address: 317 Old Mill Rd
  • Address - House Number: 317
  • Address - Street Name: Old Mill
  • Address - Suffix Type: Rd
  • State: NY
  • City Name: Smithtown
  • Zip Code: 11787

Valuation

    Tax

  • Tax Year: 2023
  • Tax Amount: $306,828
  • Tax Rate Code Area: 473401

    Appraisal Valuation

  • Standard Deviation: 0.2358
  • Valuation Date: Mar 20, 2024
  • Confidence Score: 52
  • Final Value: 1,702,662
  • High Value: 2,104,228
  • Low Value: 1,301,095

    Market Valuation

  • Market Total Value: $19,949
  • Market Land Value: $1,782
  • Market Improvement Value: $18,167

    Assessments Valuation

  • Assessed Year: 2023
  • Assessed Total Value: $17,355
  • Assessed Land Value: $1,550
  • Assessed Improvements Value: $15,805

    Sales

  • Current Sale Contract Date: Aug 07, 2020
  • Current Sale Recording Date: Oct 22, 2020
  • Current Sale Price:
  • Current Sale Document Type: 27

    Financing

  • First Mortgage Financing Type: ADJ
Data used for valuation calculations is provided by RealtyHop, and other third party sources

Comparables

Unit
Status
Type
Beds
Baths
ft²
Price/ft²
Asking Price
Listed On
Closing Price
Sold On
HOA + Taxes

About Nissequogue


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Frequently Asked Questions

When was property at 317 Old Mill Road built and last sold?
The property at 317 Old Mill Road was built in 2023 and last sold on Aug 7, 2020 for $400,000.
How much is this home worth?
The estimated value of the home located at 317 Old Mill Road is $2,792,131.
What are some comparable homes to 317 Old Mill Road?
There are currently no comparable homes to 317 Old Mill Road.

Nearby Counties