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3421 4th StreetBoulder, CO 80304

For Sale

$6,800,000

Smart Buyer Rebate $68,000

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.

Listed by Kathleen Haas

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License #IRP00465

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Colorado Realty 4 Less, LLC

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970-531-7448

Last updated March 14, 2026

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Source: REcolorado #IR1053821

Listing Facts

  • TypeSingle-family
  • NeighborhoodJuniper - Kalmia
  • Bedrooms6
  • Bathrooms5
  • Days on Prevu2
  • Taxes$26,030/year
  • Size5,022 sqft
  • Price per sqft$1,354

Amenities

  • Dishwasher
  • Private Outdoor Space
  • Parking

Location

Mortgage Calculator

Listing History

03/13/2026
Listed by Colorado Realty 4 Less, LLC
$6,800,000

Property Details for 3421 4th Street

Exterior

Construction

  • Roof: Composition
  • Structure Type: House
  • Year Built: 1990
  • Architectural Style: Contemporary
  • Construction Materials: Frame, Wood Siding

Features

  • Direction Faces: East
  • Fencing: Fenced, Partial
  • Patio And Porch Features: Deck, Patio
  • Road Frontage Type: Public
  • View: Mountain(s)

Measurements

  • Building Area Total: 5,198
  • Lot Features: Ditch, Open Space, Rolling Slope, Sprinklers In Front
  • Lot Size Acres: 0.60
  • Lot Size Square Feet: 26,072

Financial

Taxes

  • Parcel Number: R0108936
  • Tax Annual Amount: $26,030.00
  • Tax Year: 2025

Interior

Features

  • Appliances: Dishwasher, Disposal, Down Draft, Microwave, Oven, Refrigerator, Self Cleaning Oven
  • Fireplace Features: Family Room, Gas, Gas Log, Living Room
  • Interior Features: Eat-in Kitchen, Five Piece Bath, Open Floorplan, Vaulted Ceiling(s), Walk-In Closet(s)
  • Spa Features: Bath

Measurements

  • Living Area: 5,022

Rooms

  • Basement: Daylight, Full
  • Has Basement: Yes
  • Bathrooms Full: 2
  • Bathrooms Half: 1
  • Bathrooms Three Quarter: 2
  • Bathrooms Total Integer: 5
  • Bedrooms Total: 6
  • Main Level Bathrooms: 2
  • Main Level Bedrooms: 1

Other

General

  • Exclusions: Furnishings and Personal Property, Water Rights Included

Location

  • Subdivision Name: Fourth Street 3403 Sub

Parking

Parking

  • Attached Garage: Yes
  • Garage Spaces: 2
  • Parking Features: Oversized
  • Parking Total: 2

Schools

Elementary School

  • Elementary School: Foothill
  • Elementary School District: Boulder Valley RE 2

High School

  • High School: Boulder
  • High School District: Boulder Valley RE 2

Middle or Junior School

  • Middle Or Junior School: Centennial

Utilities

Equipment

  • Cooling: Ceiling Fan(s), Evaporative Cooling
  • Heating: Forced Air, Hot Water, Radiant
  • Sewer: Public Sewer
  • Utilities: Cable Available, Electricity Available, Internet Access (Wired), Natural Gas Available
  • Water Source: Public

Frequently Asked Questions

How many bedrooms and bathrooms does this single-family home have?

There are 6 bedrooms and 5 bathrooms in this single-family home at 3421 4th Street.

What schools are nearby to 3421 4th Street?

Nearby schools include the Foothill Elementary School, Centennial Middle School, and Boulder High School.

Does this single-family home have parking?

Yes, there are 2 parking spaces available for 3421 4th Street.

What are the annual taxes for 3421 4th Street?

Annual taxes for this single-family home are estimated at $26,030.

How does 3421 4th Street compare to other single-family homes in Juniper - Kalmia?

This single-family home is listed 31% below the average price for single-family homes in Juniper - Kalmia and has been on the market for 37 less days than the typical home in this area.

What is the square footage on this single-family home?

According to the MLS, this listing is 5,022 sqft.

3421 4th Street is a 6-bedroom, 5-bath single-family home for sale in Boulder CO 80304. On Prevu for 2 days at $6,800,000. This residence features 5,022 square feet of living space, located in Juniper - Kalmia. The median listing price for single-family homes in this area is $4,500,000. Nearby schools include Foothill Elementary School, Centennial Middle School, and Boulder High School. Property amenities include private outdoor space, dishwasher, and parking. View other single-family home listings in Boulder.

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Full MLS Disclaimers

Rebate estimate is indicative only and based on listing price and estimated buyer's agent commission paid by owner, if applicable. Final rebates are subject to Terms of Use and may vary due to final negotiated transaction terms.