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120 Keystone St, Sun Valley, ID 83353 (MLS# 26-334170)

$4,900,000
120 Keystone St
Sun Valley, ID 83353
MLS# 26-334170

Expansive, sun-drenched pastures with Bald Mountain as your backdrop, the ultimate Sun Valley equestrian setting.
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Expansive, sun-drenched pastures with Bald Mountain as your backdrop, the ultimate Sun Valley equestrian setting. Unobstructed, panoramic views of the iconic Bald Mountain bowls from your private 52-acre ridge. A rare 52-acre offering across two separate, deeded parcels, providing unmatched privacy and versatile development or family compound potential. A signature on-site pond creates a dramatic sense of arrival, providing a natural acoustic buffer for this private Sun Valley estate, while documented geothermal potential offers a unique, sustainable amenity. Enjoy immediate visual trail reports for Sun Valley’s Bald Mountain. 120 Keystone St offers an unobstructed vantage point of the world-class ski runs and weather conditions right from your property. Captivating up-valley views showcasing the rugged beauty and pristine wilderness of Central Idaho. Dual-parcel configuration at 120 Keystone, offering significant land-use flexibility bordering Forest Service land. Preliminary analysis identifies a premier conceptual building envelope on the 18.6-acre front parcel, strategically positioned to maximize panoramic Bald Mountain views and natural solar orientation. A secluded ground-level view showcasing the private, manicured grounds and sprawling front acreage of this Sun Valley legacy estate at 120 Keystone St. The property’s private gated driveway is a scenic masterwork, offering immediate immersion into the Sun Valley backcountry and establishing 120 Keystone St as a true legacy retreat. Preliminary analysis identifies a premier conceptual building envelope on the 18.6-acre front parcel, strategically positioned to maximize panoramic Bald Mountain views and natural solar orientation. Preliminary analysis suggests a strategic opportunity to consolidate the 33.5-acre back parcel with the front acreage through a potential U.S. Forest Service (USFS) land swap, creating a more contiguous 50+ acre Sun Valley estate. Secure, gated entry ensures total privacy for this premier 52-acre Sun Valley estate, offering a rare sanctuary bordering U.S. Forest Service land. Preliminary analysis suggests a strategic opportunity to consolidate the 33.5-acre back parcel with the front acreage through a potential U.S. Forest Service (USFS) land swap, creating a more contiguous 50+ acre Sun Valley estate. Preliminary analysis suggests a strategic opportunity to consolidate the 33.5-acre back parcel with the front acreage through a potential U.S. Forest Service (USFS) land swap, creating a more contiguous 50+ acre Sun Valley estate. Preliminary analysis suggests a strategic opportunity to consolidate the 33.5-acre back parcel with the front acreage through a potential U.S. Forest Service (USFS) land swap, creating a more contiguous 50+ acre Sun Valley estate. Preliminary site analysis identifies a premier conceptual building envelope on the 33.5-acre back parcel, positioned to maximize panoramic Bald Mountain views and natural topography. Preliminary site analysis identifies a premier conceptual building envelope on the 33.5-acre back parcel, positioned to maximize panoramic Bald Mountain views and natural topography. Secure, gated entry ensures total privacy for this premier 52-acre Sun Valley estate, offering a rare sanctuary bordering U.S. Forest Service land. The property’s private gated driveway is a scenic masterwork, offering immediate immersion into the Sun Valley backcountry and establishing 120 Keystone St as a true legacy retreat. A signature year-round pond, fed by senior 1883 water rights, creates a stunning sense of arrival as you enter the private gated drive of this 52-acre Sun Valley estate. The property’s private gated driveway is a scenic masterwork, offering immediate immersion into the Sun Valley backcountry and establishing 120 Keystone St as a true legacy retreat. A signature year-round pond, fed by senior 1883 water rights, creates a stunning sense of arrival as you enter the private gated drive of this 52-acre Sun Valley estate. A rare legacy estate featuring senior 1883 water rights and on-site geothermal potential, offering a unique sustainable energy opportunity in the Sun Valley market. Springtime at 120 Keystone: 52 acres of vibrant, emerald-green hillsides and pristine mountain air, offering a truly 'private park' experience. A rare legacy estate featuring senior 1883 water rights and on-site geothermal potential, offering a unique sustainable energy opportunity in the Sun Valley market. Experience the seasonal 'green-up' of the Wood River Valley from your private ridge; a rare look at the estate's verdant landscape and geothermal-fed vitality. A private gated entrance serves as an exclusive trailhead into Keystone Gulch, providing direct backcountry access to the summit of Johnstone Peak and the surrounding wilderness. Nestled within Sun Valley’s exclusive Elkhorn neighborhood, 120 Keystone St offers a secluded mountain retreat with a private trailhead providing direct access to the Sawtooth National Forest backcountry. A private gated entrance serves as an exclusive trailhead into Keystone Gulch, providing direct backcountry access to the summit of Johnstone Peak and the surrounding wilderness. The 33.5-acre back parcel offers a strategic USFS land swap opportunity. By exchanging hillside acreage for contiguous valley floor space, an owner can significantly expand the building envelope and maximize development density at 120 Keystone St. Stunning Bald Mountain Views Near Sun Valley Resort Skiing. Privacy meets proximity at 120 Keystone St, a gated Sun Valley estate minutes from Ketchum, Bald Mountain skiing, and the best of South Central Idaho's mountain lifestyle. Utilities on site and identified locations. Detailed boundary overlay via Land.id illustrating the two deeded parcels, topography, and the seamless border with Forest Service land. Detailed boundary overlay via Land.id illustrating the two deeded parcels, topography, and the seamless border with Forest Service land. Proposed Forest Service Land Swap application. Breathtaking fall vistas overlooking the valley; a prime season to enjoy the local wildlife and the crisp mountain air from your private ridge. Breathtaking fall vistas overlooking the valley; a prime season to enjoy the local wildlife and the crisp mountain air from your private ridge.

Property Description
Discover 120 Keystone St, a premier 52-acre legacy estate for sale in the exclusive Elkhorn area of Sun Valley, Idaho. Positioned just minutes from downtown Ketchum and the Sun Valley Resort, this rare dual-parcel landholding--comprising 18.6 and 33.5 acres--offers an unparalleled opportunity for a private equestrian compound or a boutique luxury residential development.

Details
Maps
Documents
Location, Tax and Misc
Legal: Elkhorn 46, Keystone 41 A, Carbon Hill 74 A, SEC 15 4N 18E
List Price Per Acres: 94230.77
Taxes: 1206.84
Tax Year: 2025
Lot / Acreage Info
Parcel Acres Apx: 52
Parcel Size Per: Realtor
Remarks & Misc
Possession: On Closing
General Property Description
Realtor.com: Vacant Land
Waterfront if Appcbl: Yes
Sub Type: Single Family Residence
Geo Lat: 43.677231
Geo Lon: -114.303313
Contract Info
Concession Negotiable: Yes
Concession Remarks: Please Call Listing Agent.
Directions: Located at the gated, private terminus of Keystone Street within the exclusive Elkhorn community of Sun Valley, Idaho.
Status: Active
List Date: 2026-03-12
Documents
Other: 1
Features Exterior
Barn/Shed: 1
Corral: 1
Deeded Water Rights: 1
Fence: 1
Leased Propane Tank: 1
Outbuildings: 1
Undergrnd Utilities: 1
Views: 1
Horses Permitted: 1
Road Access
Easement: 1
Private: 1
Road Surface
Dirt: 1
Terms
1031: 1
Cash: 1
OWC: 1
Waterfront
Pond: 1
See Realtor Remarks: 1
Wetlands: 1
Zoning
BC/R-10: 1
Other Disclosures
Avalanche: 1
Wetlands: 1
Utilities at Road
Electric: 1
Telephone: 1
Utilities On Site
Electric: 1
Septic: 1
Telephone: 1
Well-Individual: 1
Location Tax and Misc
Current Price: $4,900,000
Area: Elkhorn in Sun Valley
Street Number: 120
Street Name: Keystone
Street Suffix: St
State/Province: ID
Zip Code: 83353
County: Blaine
Subdivision: Other
Assessor's Parcel #: RP1M0000000750
List Price: $4,900,000
Lot Acreage Info
Parcel SqFt Apx: 2265120
Property Features
Zoning: BC/R-10
Road Surface: Dirt
Road Access: Easement; Private
Utilities On Site: Electric; Septic; Telephone; Well-Individual
Waterfront: Pond; See Realtor Remarks; Wetlands
Features Exterior: Barn/Shed; Corral; Deeded Water Rights; Fence; Outbuildings; Undergrnd Utilities; Views; Horses Permitted; Leased Propane Tank
Documents: Other
Other Disclosures: Avalanche; Wetlands
Terms: 1031; Cash; OWC
Utilities at Road: Electric; Telephone
Supplements
Bordering U.S. Forest Service land, the property provides direct, private canyon access for horseback riding, hiking, and outdoor recreation right from your back door. Appraised at $10.5M, this Sun Valley real estate asset combines pristine natural amenities with exceptional utility. The land is anchored by senior 1883 water rights for irrigation and stock, a high-yield well, and a serene pond with on-site geothermal potential. Ready for immediate development, the property features BC/R-10 zoning with patented mining claims, along with installed infrastructure including well, septic, and buried power. Significant value-add and investment upside include a prospective 18-acre USFS land swap to expand contiguous acreage, as well as a recent site analysis indicating potential for a third building site to increase overall density. As one of the last large private landholdings in a supply-constrained Blaine County market, the seller is offering flexible acquisition terms, including owner financing (owner carry paper) for up to five years with 50% down. Search "120 Keystone St Sun Valley" on YouTube to view complete video tours.
Listing Office: Keller Williams Sun Valley Southern Idaho
Listing Agent: James Tautkus

Last Updated: August - 31 - 2026

The information being provided is for consumers' personal, non-commercial use and may not be used for any purpose other than to identify prospective properties. This serves as notice to those using the website that they may not use the data found here as a basis for a business enterprise. Information provided by Sun Valley Board of Realtors Multiple Listing Service is deemed reliable but not guaranteed. Property of the Sun Valley Board of Realtors. Information provided by Sun Valley Board of Realtors Multiple Listing Service is deemed reliable but not guaranteed. The information on this sheet has been made available by the MLS and may not be the listing of the provider.

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