3421 4th St, Boulder, CO

$6,800,000

Previous Next

6

Beds

5

Baths

5,198

Square feet

0.60

Acres

About 3421 4th St

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.

Open House

Sat, Sep 5th, 2026 @ 12pm - 4pm
Sun, Sep 6th, 2026 @ 12pm - 4pm
Sat, Sep 12th, 2026 @ 12pm - 4pm
Sun, Sep 13th, 2026 @ 12pm - 4pm
Sat, Sep 19th, 2026 @ 12pm - 4pm
Sun, Sep 20th, 2026 @ 12pm - 4pm
Sat, Sep 26th, 2026 @ 12pm - 4pm
Sun, Sep 27th, 2026 @ 12pm - 4pm

Features of 3421 4th St

MLS® # 1053821
Price $6,800,000
Bedrooms 6
Bathrooms 5.00
Full Baths 2
Half Baths 1
3/4 Baths 2
Square Footage 5,198
Acres 0.60
Year Built 1990
Type Residential
Sub-Type Single Family Residence
Style Legal Conforming, Contemporary
Status Active

Community Information

Address 3421 4th St
Area Boulder
Subdivision Fourth Street 3403 Sub
City Boulder
County Boulder
State CO
Zip Code 80304

Amenities

Utilities Natural Gas Available, Electricity Available, Cable Available, High Speed Avail
Parking Garage Door Opener, Attached
# of Garages 2
Garages Attached
View Hills
Is Waterfront No
Has Pool No

Interior

Interior Features Eat-in Kitchen, Separate Dining Room, Cathedral Ceiling(s), Open Floorplan, Walk-In Closet(s)
Appliances Gas Range, Down Draft, Self Cleaning Oven, Dishwasher, Refrigerator, Microwave, Disposal, Fire Alarm
Heating Forced Air, Hot Water, Zoned, Radiant, 2 or more Heat Sources
Cooling Evaporative Cooling, Ceiling Fan(s)
Fireplace No
Fireplaces Two or More, Gas, Gas Log, Living Room, Family Room
Stories Four

Exterior

Exterior Features Sprinkler System, Oversized Garage
Lot Description Wooded, Evergreen Trees, Deciduous Trees, Sloping Lot, Abuts Ditch, Abuts Public Open Space, House Faces East, Paved, Water Rights Included
Roof Composition
Construction Frame, Wood Siding

School Information

District Boulder Valley Dist RE2
Elementary Foothill
Middle Centennial
High Boulder

Additional Information

Days on Market 173
Zoning SFR
Foreclosure No
Short Sale No
RE / Bank Owned No

Listing Details

AgentKathleen Haas
OfficeColorado Realty 4 Less, LLC

Listing Map

Request a Showing

Provide a valid email address.
When would you like to view this property?