21 Walnut St #M, Boston, MA, 02108
About This Home
Just off iconic Chestnut Street, this exceptional Beacon Hill maisonette offers the rare combination of a private entrance, landscaped garden, and secluded patio in the coveted South Slope. Rich in architectural detail and filled with natural light from abundant windows and skylights, this elegant duplex lives like a private townhouse. The fireplaced living room opens to the private terrace, while the beautifully updated kitchen features stone countertops, custom cabinetry, and stainless appliances. A spacious den overlooking the garden provides an ideal home office or dining area. Upstairs are two generous skylit bedrooms, including a tranquil primary suite with large closets and a marble bath with radiant heated floors. Hardwood floors, Miele washer/dryer, air conditioning, and deeded storage complete this rare offering, just moments from Boston Common, the Public Garden, the Charles River,Esplanade and all and restaurants along nearby Charles St and the Back Bay.
Getting Around
Walker's Paradise
Rider's Paradise
BikeableSchools
Construction
Condition
- Year built: 1875
Materials
- Construction materials: Brick
Type & Style
- Home type: Townhouse
- Property subType: Condominium,Townhouse
Interior
Appliances
- Laundry features: In Unit
Bathroom1
- Features: Bathroom - Full
- Level: Second
- Area: 54
Bathroom2
- Features: Bathroom - Full, Bathroom - With Shower Stall
- Level: Second
- Area: 30
Bedroom2
- Features: Skylight, Closet, Flooring - Hardwood, Window Seat
- Level: Second
- Area: 117
Bedrooms & Bathrooms
- Bedrooms: 2
- Bathrooms: 2
- Full bathrooms: 2
Dining Room
- Level: First
- Area: 154
Features
- Closet,Entrance Foyer
- Door features: French Doors
- Flooring: Flooring - Stone/Ceramic Tile
- Number of fireplaces: 1
- Fireplace features: Living Room
- Fireplace: Yes
- Finished area above ground: 1,038
- Common walls with other units/homes: Corner
Heating & Cooling
- Heating features: Baseboard
- Cooling features: Heat Pump
Interior Area
- Total structure area: 1,038
- Total interior livable area: 1,038 sqft
Kitchen
- Features: Flooring - Stone/Ceramic Tile
- Level: First
- Area: 165
Living Room
- Features: Flooring - Hardwood, French Doors, Exterior Access
- Level: First
- Area: 216
Master Bathroom
- Features: Yes
Master Bedroom
- Features: Skylight, Closet, Flooring - Hardwood
- Level: Second
- Area: 154
Property
Accessibility
- Accessibility features: No
Details
- Parcel number: W:05 P:01573 S:006,4758964
- Zoning: CD
- Other equipment: Intercom
Features
- Entry location: Unit Placement(Courtyard)
- Patio & porch: Patio - Enclosed
- Exterior features: Courtyard,Patio - Enclosed,Garden
- Fencing: Security
Lot
- Lot size: 1,038 sqft
Parking
- Parking features: On Street
- Has uncovered spaces: Yes
Climate Risk is Financial Risk
Every home has a financial story beyond the listing price. Below, you’ll see the climate risks that could affect this property — and in Bills & Affordability, how those risks may influence repairs, insurance, utilities, and long-term value.
Biggest Threats for This Home
- Heat Wave
- Inland Flooding
- Lightning
- Tsunami
How This Home’s Risks Compare
FEMA Declared Disasters Across Massachusetts Counties
Understanding the Costs
Financial advisors generally recommend spending no more than 30% of your gross household income on housing costs. In practice, many households stretch to 35% or beyond — especially in high-cost markets.
Estimated Costs Today
| Monthly | Annual | |
|---|---|---|
| Mortgage | $9,101 | $109,212 |
| Home Insurance * | $334 | $4,008 |
| Property Taxes | $1,035 | $12,420 |
| Electricity | $354 | $4,259 |
| Total | $10,824 | $129,888 |
Income You'd Need if You Spent...
Massachusetts FAIR Plan Programs
How Costs Could Change Over Time
Climate risk is quickly impacting all of the major home ownership costs. Adjust the growth rates and percentage of income spent on housing below to see how your housing costs could change over the next 10 years — and what income you'd need to keep up.
Comparing Against the Market
Price Per Sq Ft
vs Other Active Listings
Avg $/sqft
vs Homes Sold Last Month
Median $/sqft
Current Market Trends
Median Price Per Square Foot
The median price per square foot of homes sold in this area each month. Compare this to this listing's price per square foot to gauge whether the home is priced in line with recent sales.
Historicals for This Listing
Zestimate History ($/sqft)
Price History
| Date | Event | Price |
|---|---|---|
| 2026-07-14 | Listed for sale | $1,800,000 |
| 2022-06-15 | Sold | $1,600,000 |
| 2021-06-30 | Listing removed | $1,775,000 |
| 2021-04-30 | Listed for sale | $1,775,000 |
| 2019-08-05 | Sold | $1,775,000 |
For Sale by Agent
View on Zillow