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CondominiumResidential
$757,121$796 / ft²
TopHap EstimateOur estimate of what this home would sell for today, based on nearby sales, the home's size and features, and local price trends. It is a starting point, not an appraisal.· confidence 94How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Sep 24, 2026
Last sold for $531,000 on Oct 27, 2014

21 MAIN ST

CHARLESTOWN, MA 02129
Building report
2
Beds
1
Baths
951 ft²
Living AreaTotal finished area of the structures, from county records. Some counties include shared space like hallways or a building gym, so it may not match a listing.
951 ft²
Lot SizeThe size of the land the home sits on, from county records.
1987
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.
4
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.

Valuation

$757K
$714K low$800K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$531,000 · Oct 27, 2014

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$7,258 (2025)
Assessed ValueThe value the county assigns to this home to calculate property tax. It is often lower than what the home would sell for.$626,800 (2025)
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$626,800
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$771,020

Climate Risk

Projected Flood DepthHow deep a serious flood is expected to get here at some point in the next 30 years. Shown in inches.36 in
30-Year Flood ChanceThe chance of at least one serious flood here in the next 30 years, not in any single year.49%
FEMA Flood ZoneFEMA's flood zone for this address. Zones starting with A or V are high risk, and lenders usually require flood insurance there.minimal

Scores 0–100; higher = greater projected risk.

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Condominium
CountySUFFOLK
Lot (acres)The size of the land the home sits on, from county records.0.02
RoofThe main material covering the roof, such as asphalt shingle or tile.Asphalt
HeatingThe type of heating system in the home.Electric
CoolingThe type of cooling or air conditioning in the home.Yes
FireplaceWhether the home has a fireplace, and what kind.Yes
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(14)

Sales and refinances filed with the county for this home. Not every transfer is a normal sale, so check the type before comparing prices.

Assigned SchoolsThe public schools this address is zoned for. Boundaries change, so confirm with the district before you count on it.

E
Harvard / Kent Elementary SchoolC-
Elementary · Grades PK–5 · 0.3 mi
M
Warren / Prescott K-8 SchoolA-
Middle · Grades PK–8 · 0.3 mi
H
Charlestown High SchoolD+
High · Grades 9–12 · 0.5 mi

District: Boston School District

Neighborhood · ZIP 02129These are comparison scores, not percentages. 100 equals the national average, so 150 means about 50% above average.

CrimeLocal crime compared with the rest of the country, where 100 is average. It reflects things like population density, income, and how crime gets reported.89
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.101
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.73

Index scale: 100 = US average (tick). Lower is better.

Homes occupiedThe share of homes here that someone lives in. The rest sit empty, including vacation and for-sale homes.94%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.35%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.8.3%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.3%
PopulationHow many people live in this area.18,397
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.10,594 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$152,177
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$178,903
Average tempThe average temperature here across a full year.50°F
Annual precipHow much rain and melted snow falls here in a typical year.46 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.58%

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Data by ATTOM. Valuations are automated estimates, not appraisals. Photos from Google Street View and may not depict the current property state.

How this home compares

21 Main St measured against every home in its neighborhood, its ZIP code and its county, using county assessor records refreshed nightly. A home can stand out in one of those areas and look ordinary in another, because each one holds a different mix of homes.

  • Worth less than 73% of homes in Charlestown 02129
  • Costs less per square foot than 82% of homes in Charlestown 02129
  • Smaller than 75% of homes in Suffolk County
  • Has a smaller lot than 78% of homes in Suffolk County
  • Newer than 82% of homes in Suffolk County

What homes are worth in Charlestown 02129

Each bar is how many homes fall in that price range. The marker is this home.

This home
$447K$2.9M

This home is worth more than 27% of homes in Charlestown 02129.

How it measures up in Charlestown 02129

The dot is this home. The mark in the middle is the typical home in Charlestown 02129.

Estimated value$757,121
CheaperTypical $1,035,126Pricier

Pricier than 27% of homes nearby

Price per ft²$796
CheaperTypical $942Pricier

Pricier than 18% of homes nearby

Living area951 ft²
SmallerTypical 1,200 ft²Bigger

Bigger than 33% of homes nearby

Lot size951 ft²
SmallerTypical 1,133 ft²Bigger

Bigger than 33% of homes nearby

Year built1987
OlderTypical 1899Newer

Newer than 78% of homes nearby

How 21 Main St ranks against every home in each area.
MeasureThis homeCharlestown 02129Suffolk County
Estimated valuepricier than$757,12127% of homes57% of homes
Price per ft²pricier than$79618% of homes67% of homes
Living areabigger than951 ft²33% of homes25% of homes
Lot sizebigger than951 ft²33% of homes22% of homes
Year builtnewer than198778% of homes82% of homes

About 21 Main St

How much is 21 Main St, Charlestown, MA worth?

The TopHap Estimate for 21 Main St, Charlestown, MA is $757,121 as of Sep 24, 2026. The likely range is $714,100 to $800,142. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 21 Main St, Charlestown, MA last sell?

21 Main St, Charlestown, MA last sold on Oct 27, 2014 for $531,000, according to the county's recorded deed. TopHap holds 8 recorded sales for this parcel.

How big is 21 Main St, Charlestown, MA?

21 Main St, Charlestown, MA has 2 bedrooms, 1 bathrooms, 951 square feet of living space and a 0.02-acre lot.

When was 21 Main St, Charlestown, MA built?

21 Main St, Charlestown, MA was built in 1987, making it 39 years old. The building has 2 stories.

What schools serve 21 Main St, Charlestown, MA?

21 Main St, Charlestown, MA is assigned to Harvard / Kent Elementary School (elementary), rated C-; Warren / Prescott K-8 School (middle), rated A-; Charlestown High School (high), rated D+. All sit in Boston School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 21 Main St, Charlestown, MA compare to other homes in Charlestown 02129?

Among the 5,261 homes in Charlestown 02129, it is worth more than 27% of them ($757,121 against a typical $1,035,126), its price per square foot is higher than 18% of them ($796 against a typical $942), it is bigger than 33% of them (951 ft² against a typical 1,200 ft²), its lot is bigger than 33% of them (951 ft² against a typical 1,133 ft²) and it is newer than 78% of them (1987 against a typical 1899). Measured against all of Suffolk County, it is worth more than 57% of homes there. These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 21 Main St, Charlestown, MA?

The 2025 property tax bill for 21 Main St, Charlestown, MA was $7,258. The county assessed it at $626,800.

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