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3421 4th Street, Boulder, CO, 80304

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MLS #RECIR1053821 image #0

Open House Aug 02, 2026
12:00 – 04:00
Open House Aug 02, 2026
12:00 – 04:00
Open House Aug 01, 2026
12:00 – 04:00

3421 4th Street, Boulder, CO, 80304

6 Beds
5 Baths
5,198 SqFt
0.6 Acres

Listing Id

RECIR1053821
$6,800,000

Newlands Sanctuary on Mt. Sanitas Open Space Step onto the 600-square-foot deck and look up. Mt. Sanitas rises 1,300 feet from your backyard gate, private access to the Goat Trail. No driving. No parking. Just you, your coffee, and maybe a 4-legged friend who will make sure you don’t skip it. This premier property is one of eight homes backing directly to open space. In 21 years, only one has changed hands. Hidden behind a 70-yard tree-lined driveway on a 0.6-acre lot (2.5x standard), this is widely regarded as one of Boulder’s best addresses, served by top rated schools.The 5,200-square-foot residence features 20-foot ceilings with west-facing glass framing Mt. Sanitas, white oak floors, two fireplaces, and a library overlooking the property’s seven heritage apple trees. Six bedrooms plus office (convertible seventh) include three distinct suites: the primary en-suite with a stunning view; a garden-level walkout in-law addition (2005, 12′ ceilings) with separate entrance, private patio, and dedicated office-ideal for multigenerational living or guests-plus a basement suite with whirlpool bath. Outside you will discover a deep wrap-around porch beneath a 60-foot silver maple, flower and vegetable gardens, and the historic Silver Lake Ditch with 12,000 gallons daily water rights. Sundance Film Festival arrives January 2027, venues minutes away providing a chance at an incredible rental income opportunity and under the Augusta Rule, 14 days of rental income may be tax-free. Roof replaced 2019. New carpet. Heated two-car garage. No HOA. No covenants. For those who know Newlands: this is the privacy, the lot, the view, and the trail access that almost never comes to market. For those discovering Boulder for the first time: welcome to the neighborhood the locals covet most.

Property Details
Price:
$6,800,000
MLS #:
RECIR1053821
Status:
Active
Beds:
6
Baths:
5
Type:
Single Family
Structure:
House
Subdivision:
Fourth Street 3403 Sub
Finished Sq Ft:
5,022
Total Sq Ft:
5,198
Lot Size:
26,072 sqft / 0.60 acres (approx)
Year Built:
1990
ContemporaryFourth Street 3403 SubBoulder Valley Re 2FoothillCentennialBoulderMountain(s)
Interior
Above Grade Finished Area
3927
Appliances
Dishwasher, Disposal, Down Draft, Microwave, Oven, Refrigerator, Self Cleaning Oven
Bathrooms
2 Full Bathrooms, 2 Three Quarter Bathrooms, 1 Half Bathroom
Below Grade Finished Area
1095
Below Grade Unfinished Area
176
Cooling
Ceiling Fan(s), Evaporative Cooling
Heating
Forced Air, Hot Water, Radiant
Interior Features
Eat-in Kitchen, Five Piece Bath, Open Floorplan, Vaulted Ceiling(s), Walk-In Closet(s)
Levels
Three Or More
Main Level Bathrooms
2
Main Level Bedrooms
1
Exterior
Architectural Style
Contemporary
Attached Garage YN
1
Construction Materials
Frame, Wood Siding
Direction Faces
East
Fencing
Fenced, Partial
Garage Spaces
2
Lot Features
Ditch, Open Space, Rolling Slope, Sprinklers In Front
Parking Features
Oversized
Parking Spots
2
Parking Total
2
Patio And Porch Features
Deck, Patio
Roof
Composition
Security Features
Smoke Detector(s)
Spa Features
Bath
View
Mountain(s)
Schools
School District:
Boulder Valley RE 2
Elementary School:
Foothill
Middle School:
Centennial
High School:
Boulder
Financial
Tax Year
2025
Taxes
$26,030

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3421 4th Street
Boulder, CO