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$6,800,000

  • For Sale
  • Active
  • Single Family
  • 6 Beds
  • 2 Full Baths
  • 3 Partial Baths
  • 5,198 Sq. Ft.
  • 2 Car Garage
  • Updated 7 days ago

Next open house:

Open House: 12:00 PM - 4:00 PM

Saturday 4/4 12:00 PM - 4:00 PM

3421 4th St,Boulder, CO 80304

3421 4th StBoulderCO80304

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  • Open House: 12:00 PM - 4:00 PM

    Saturday 4/11 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
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    Sunday 4/12 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
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    Saturday 4/18 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
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    Sunday 4/19 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 4/25 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
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    Sunday 4/26 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
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    Saturday 5/2 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
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    Sunday 5/3 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 5/9 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
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    Sunday 5/10 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 5/16 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Sunday 5/17 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 5/23 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Sunday 5/24 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 5/30 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Sunday 5/31 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 6/6 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Sunday 6/7 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 6/13 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Sunday 6/14 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 6/20 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Sunday 6/21 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Saturday 6/27 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
  • Open House: 12:00 PM - 4:00 PM

    Sunday 6/28 12:00 PM - 4:00 PM

    3421 4th St,Boulder, CO 80304
    3421 4th StBoulderCO80304
See This Home
Save This Home
See This Home
Save This Home
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.

Full Property Details for 3421 4th St

General

  • Price: $6,800,000
  • Taxes: $26,030 (2025)
  • Status: Active
  • Type: Single Family
  • Source: IRES
  • MLS ID: 1053821
  • Updated: 3/26/2026
  • Added to Site: 21 day(s) ago

Interior

  • Interior Features: Eat-In Kitchen, Separate Dining Room, Cathedral Ceiling(s), Open Floorplan, Walk-In Closet(s)
  • Fireplace: Yes
  • Fireplace(s): Two or More, Gas, Gas Log, Living Room, Family Room
  • Appliances: Gas Range, Down Draft, Self Cleaning Oven, Dishwasher, Refrigerator, Microwave, Disposal, Fire Alarm

Rooms

Bathrooms

  • Total Bathrooms: 5
  • Full Bathrooms: 2
  • 3/4 Bathrooms: 2
  • Half Bathrooms: 1
  • Basement Baths: 1

Bedrooms

  • Total Bedrooms: 6

Additional Information

  • Spa: Yes
  • Spa Description: Bath

Exterior

  • Exterior Features: Sprinkler System, Oversized Garage
  • Porch/Patio/Deck: Patio, Deck

Parking

  • Garage: Yes
  • Attached garage: Yes
  • Garage Spaces: 2
  • Parking Features: Garage Door Opener, Attached
  • Garage Description: Attached

Location

  • Area: Boulder
  • County: Boulder
  • Subdivision: Fourth Street 3403 Sub
  • Driving Directions: From Broadway, turn left on Juniper Ave. Turn right on 4th St. Property on left side.

School Information

  • School District: Boulder Valley Dist RE2
  • Elementary School: Foothill
  • Middle School: Centennial
  • High School: Boulder

Heating & Cooling

  • Cooling Type: Evaporative Cooling, Ceiling Fan(s)
  • Heating Type: Forced Air, Hot Water, Zoned, Radiant, 2 or more Heat Sources

Utilities

  • Gas: Yes
  • Gas: Xcel
  • Sewer: Public Sewer
  • Water: City
  • Utility Description: Natural Gas Available, Electricity Available, Cable Available, High-Speed Internet Available

Structural Information

  • Architectural Style: Legal Conforming, Contemporary
  • Construction: Frame, Wood Siding
  • Exterior Const.: Frame, Wood Siding
  • Basement: Yes
  • Basement Desc.: Full, Partially Finished, Daylight
  • Roof: Composition
  • Square Feet: 5,198
  • Sq. Ft. Source: Other
  • Living Area: 5,022 Sq. Ft.
  • Year Built: 1990

Lot Features

  • Property View: Hills
  • Lot Size (Acres): 0.6
  • Lot Size (Sq. Ft.): 26,072
  • Frontage: City Street
  • Street/Road Desc.: Asphalt
  • Fence: Yes
  • Lot Features: Wooded, Evergreen Trees, Deciduous Trees, Sloping Lot, Abuts Ditch, Abuts Public Open Space, House Faces East, Paved, Water Rights Included
  • Potential Use: Single-Family
  • Zoning: SFR
  • Fencing (Description): Partial, Fenced, Wood, Chain Link

Financial Considerations

  • Tax Amount: $26,030
  • Tax Year: 2025
  • Terms: Cash, Conventional, Owner Pays Points, 1031 Exchange

Disclosures and Reports

  • Special Conditions: Other Owner
  • Exclusions: Furnishings and Personal Property
  • Property ID: R0108936

Listed by Colorado Realty 4 Less, LLC (970) 531-7448

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Listing agent

— 3421 4th St —

  • Colorado Realty 4 Less, LLC

    970-531-7448

9705317448

Get Pre-Approved Today

Be ready to buy your new home!

with our affiliated lender
NMLS#: 1598647

Get Pre-Approved

Be ready to buy your new home!

with our affiliated lender
NMLS#: 1598647

Get Pre-Approved

Schools serving 3421 4th St

School District:Boulder Valley School District Re-2
NameGradesDistance
Foothill Elementary School
1001 Hawthorn Avenue, Boulder, CO 80304
K-50.5 mi
Centennial Middle School, Boulder, CO
2205 Norwood Avenue, Boulder, CO 80304
6-81.3 mi
Boulder High School
1604 Arapahoe Avenue, Boulder, CO 80302
9-121.9 mi
Disclaimer: School attendance boundaries provided by ATTOM Data Solutions and are for reference only. Contact the school directly to verify enrollment eligibility.

Price & Sales History for 3421 4th St Get Price Alerts and Save Property

Date
Details
Price
Change
Source
3/13/2026
Listed
$6,800,000
288.57%
MLS
9/16/2004
Sold
$1,750,000
—
Public Record
Get Price Alerts and Save Property
Disclaimer: Historical sales information is derived from public records provided by the county offices. Information is not guaranteed and should be independently verified.

Tax History for 3421 4th St

Year
Property Taxes
Change
Tax Assessment
Change
2025
$26,030
-3%
$272,994
-11%
2024
$26,869
2%
$305,728
-1%
2023
$26,402
13%
$309,412
24%
2022
$23,332
6%
$248,761
-3%
2021
$22,028
—
$255,920
28%
2021
$22,028
29%
$199,185
—
2019
$17,073
7%
$199,185
8%
2018
$15,932
3%
$183,758
—
2017
$15,433
10%
$183,758
13%
2016
$14,091
6%
$162,774
—
2015
$13,343
38%
$162,774
45%
2014
$9,681
2%
$112,602
—
2013
$9,468
—
$112,602
—
View All
Disclaimer: Historical tax information is derived from public records provided by the county offices. Information is not guaranteed and should be independently verified.

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Listed by Colorado Realty 4 Less, LLC (970) 531-7448

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3421 4th St, Boulder, CO 80304 (MLS# 1053821) is a Single Family property with 6 bedrooms, 2 full bathrooms and 3 partial bathrooms. 3421 4th St is currently listed for $6,800,000 and was received on March 13, 2026. Want to learn more about 3421 4th St? Do you have questions about finding other Single Family real estate for sale in Boulder? You can browse all Boulder real estate or contact a Coldwell Banker agent to request more information.

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