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Listing provided courtesy of The Agency - Boulderas Distributed by MLSGrid- MLS# IR1051043MLS Provider

3633 21st StreetBoulder, CO 80304

Single Family · 7 Beds · 3 Full Baths · 1 Half Bath · 1 Three Quarter Bath · 6,988 Sq. ft. | 0.81 Acres
$10,000,000 Active

3633 21st Street Overview

Time on Site:
143 days
Visits:
3

Exquisite secluded sanctuary in the heart of Carolyn Heights. Tucked into one of Boulder's most prestigious enclaves, this estate offers a rare fusion of luxury, privacy, and relaxed sophistication. Set on a serene, tree-lined .81-acre level lot, this 7-bedroom, 5-bathroom oasis is where inspired design meets effortless living. Stunning views of the Flatirons awaken you each morning from your bed. Those same views tease your senses from the expansive patios with fully retractable doors that blur the lines from inside to outside. Bathed in natural light from soaring windows and skylights, every detail has been thoughtfully curated. Custom walnut doors and paneling welcome you into the home and invite you to explore. The chef's kitchen is a showstopper-featuring custom cabinetry, an oversized marble island, and top-of-the-line Thermador appliances. The open-concept layout flows seamlessly into a lush backyard oasis, perfect for gatherings or quiet moments of retreat by the fire pit. The primary suite is a haven unto itself with vaulted ceilings, a spa-inspired bath, spacious walk-in closet, and private deck access. With multiple flexible living spaces-including a dedicated home office and media room, this home is ready to adapt to your every need. Located minutes from North Boulder's best hiking trails, cycling routes, farmers markets, and local eateries-yet nestled in the peaceful privacy of a mature, sought-after neighborhood. Elevated living starts here. LIVE BOULDER, LOVE BOULDER! Original home built in 1987. Home had a studs up remodel that was completed in early 2024.

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3633 21st Street Facts & Features

  • Type Single Family
  • Sq. ft. 6,988
  • Price/Sq.ft. $1,431
  • Lot 0.81 Acres

Details

General

Association/HOA

  • Association: false

School Information

  • School District: Boulder Valley RE 2
  • Elementary School: Columbine
  • Middle Or Junior School: Centennial
  • High School: Boulder

Listing Information

  • Concessions: No

Building Information

  • Year Built: 2024

Location/Region

  • Country: US
  • County Or Parish: Boulder
  • Subdivision Name: 21st/Linden Sub

Tax Information

  • Tax Annual Amount: 29641
  • Tax Year: 2025

General Information

  • Exclusions: Sellers personal property and any staging items
  • Listing Terms: Cash,Conventional
  • Ownership: Individual
  • Parcel Number: R0004105
  • Possible Use: Residential
  • Property Condition: New Construction
  • Property Sub Type: Single Family Residence
  • Property Type: Residential
  • Zoning: RES

Interior

Parking Information

  • Garage Spaces: 3

Beds/Baths

  • Bathrooms Full: 3
  • Bathrooms Half: 1
  • Bathrooms Three Quarter: 1
  • Bathrooms Total: 5
  • Bedrooms Total: 7

Building Interior

  • Above Grade Finished Area: 4798
  • Below Grade Finished Area: 2190
  • Building Area Source: Assessor
  • Building Area Total: 6988

General Information

  • Appliances: Dishwasher,Disposal,Dryer,Microwave,Oven,Refrigerator,Washer
  • Cooling: Air Conditioning-Room,Ceiling Fan(s)
  • Fireplace Features: Gas
  • Flooring: Tile,Wood
  • Heating: Hot Water,Radiant
  • Interior Features: Eat-in Kitchen,Five Piece Bath,Kitchen Island,Open Floorplan,Pantry,Vaulted Ceiling(s),Walk-In Closet(s)
  • Levels: Tri-Level
  • Living Area: 6988
  • Main Level Bathrooms: 1
  • Main Level Bedrooms: 0
  • Security Features: Fire Sprinkler System,Smoke Detector(s)
  • Window Features: Skylight(s)

Exterior

Parking Information

  • Parking Features: Oversized
  • Parking Total: 3

Lot Information

  • Lot Features: Level,Sprinklers In Front
  • Lot Size Acres: 0.81
  • Lot Size Square Feet: 35311
  • Vegetation: Wooded
  • Water Source: Public

Waterfront/View

  • View: Mountain(s)

Building Exterior/Construction

  • Architectural Style: Contemporary
  • Attached Garage: true
  • Construction Materials: Frame
  • Direction Faces: South
  • Patio And Porch Features: Deck,Patio
  • Roof: Composition
  • Structure Type: House

General Information

  • Fencing: Fenced,Partial
  • Sewer: Public Sewer
  • Utilities: Electricity Available,Natural Gas Available

Room Information

Room: Bathroom Full

  • Level: Basement

Room: Bedroom

  • Level: Lower
  • Length: 14
  • Width: 12
  • Description: Carpet

Room: Game Room

  • Level: Lower
  • Length: 35
  • Width: 18
  • Description: Carpet

Room: Bathroom Half

  • Level: Main

Room: Dining Room

  • Level: Main
  • Length: 15
  • Width: 14
  • Description: Wood

Room: Kitchen

  • Level: Main
  • Length: 16
  • Width: 16
  • Description: Wood

Room: Laundry

  • Level: Main
  • Length: 14
  • Width: 10
  • Description: Tile

Room: Living Room

  • Level: Main
  • Length: 27
  • Width: 26
  • Description: Wood

Room: Office

  • Level: Main
  • Length: 19
  • Width: 14
  • Description: Wood

Room: Bathroom Full

  • Level: Upper
  • Features: Primary Suite

Room: Bathroom Full

  • Level: Upper

Room: Bathroom Three Quarter

  • Level: Upper

Room: Bedroom

  • Level: Upper
  • Length: 26
  • Width: 16
  • Description: Carpet
  • Features: Primary Suite

Room: Bedroom

  • Level: Upper
  • Length: 15
  • Width: 13
  • Description: Wood

Room: Bedroom

  • Level: Upper
  • Length: 22
  • Width: 11
  • Description: Carpet

Room: Bedroom

  • Level: Upper
  • Length: 15
  • Width: 13
  • Description: Carpet

Room: Bedroom

  • Level: Upper
  • Length: 15
  • Width: 14
  • Description: Wood

3633 21st Street Neighborhood

Community

80304 (Boulder) Demographics

41
Median Age
2,891
Population Density (per sq. mile)
81%
College Educated
$98,049
Estimated Median Income
7,931
Estimated Total Home Owners
3,417
Estimated Total Renters
70% / 30%
Estimated Owner / Renter Divide
2
Estimated Average Household Size
Community data courtesy of LiveBy, Inc.

Schools

School data courtesy of LiveBy, Inc. School ratings are based on a scale of 1-5, with 5 being the highest rating and 1 being the lowest rating.

3633 21st Street Monthly Cost

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* All calculations are estimates and provided by Reliance Network, for informational purposes only. Actual amounts may vary. ** Assumes 6.50% APR, 20% down payment, and conventional 30-year fixed rate first mortgage. Rates cited are for instructional purposes only; current rates are subject to change at any time without notice. You should not make any decisions based simply on the information provided. Additional required amounts such as taxes, insurance, homeowner association dues, assessments, mortgage insurance premiums, flood insurance or other such required payments should also be considered. Contact your mortgage company for current rates and additional information. Any mortgage broker or insurance agent that may appear is independent and is not affiliated with, endorsed by, or provided by the MLS.

3633 21st Street Market Data

Based on the last 30 days in this zip code

$2,503,375
Average List Price
$799
Average Price per Square Foot
46
Properties Sold
101
Average Days on Market
233
Properties for Sale
Calculations provided by Reliance Network

3633 21st Street History

Date Event Value Agent
2/6/2026Source: REColorado MLS Added to Database
February 06, 2026