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CondominiumResidential

21 Main St

CHARLESTOWN, MA 02129
1,608 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.
1
ParkingThe number of parking spaces on the property, including the garage.
Built 19875 units679–1,608 ft²
$4.5M
All units combinedThe sum of our current value estimates for every unit in the building — roughly what the whole building's homes are worth together.
$768K
Median unit valueThe middle unit value in this building by our estimate: half the units are worth more, half less.
$1110
Median $/ft²The middle price per square foot across the building's units, by our current estimates. Useful for comparing units of different sizes.

+35.2%vs the Charlestown ZIP median sale $/ft² ($821)

Sales Performance

—
Median sale (12 mo)The middle sale price among this building's units that sold in the last 12 months, from recorded deeds.
—
1-yr changeHow the building's median sale price over the last 12 months compares with the 12 months before that.
0
Sales (12 mo)Units in this building that sold in the last 12 months, from recorded arms-length deeds.
0.0%
Turnover (12 mo)The share of units that changed hands in the last 12 months. Around 4–6% a year is typical; much higher can signal investor churn or a wave of exits.
This building's own appreciationThe building's own appreciation: for every unit that sold twice (held over a year), we compute its yearly price change between the two sales and take the middle value. This is the cleanest read on how this specific building performs, because it compares each unit to itself.
+4.2%per yeartypical hold 7.0 yrsfrom 19 same-unit resales
Median sale price (yearly, all time)Every recorded arms-length sale in the building since records begin, grouped by year: the bars count sales and the line tracks the median price paid.MedianSales
19871990199619982002201220162025
Sale price per ft² (yearly, all time)The middle price per square foot across the building's units, by our current estimates. Useful for comparing units of different sizes.$/ft²
19871990199619982002201220162025

26 arms-length sales on record for this building.

Unit Mix & Floor PlansThe building's recurring floor plans, found by grouping units with identical beds, baths and square footage in county records. Larger groups are the building's standard layouts; leftover units have one-off sizes.

1 bed
3 units
2 bed
2 units
Recurring floor plansThe building's recurring floor plans, found by grouping units with identical beds, baths and square footage in county records. Larger groups are the building's standard layouts; leftover units have one-off sizes.
1 bd · 1 ba · 683 ft²
2 units
One-off layouts
3 units

Ownership & Financing

Owner-occupiedThe share of units where the owner lives in the unit, per county records. The rest are second homes or rentals.40%
Company-ownedUnits owned through an LLC, trust, or other company — a rough proxy for investor ownership.40%
Typical owner tenureThe middle number of years since each unit last changed hands — how long the current owners have been in place.10.2 yrs
Cash purchases (5 yrs)The share of purchases in the last 5 years with no mortgage recorded. High cash share is common in second-home and investor buildings.0%
Avg. loan-to-valueAverage current loan balance against unit value across the building. Low numbers mean owners hold lots of equity — a sign of financial stability.54%
Median owner equityThe middle dollar amount of equity (value minus loans) unit owners hold in this building.$753,564
Median tax billThe middle annual property tax bill among the building's units.$7,381
Pre-foreclosure noticesUnits with an active pre-foreclosure or foreclosure notice on file.0

Recent SalesThe latest recorded arms-length sales in the building, newest first.

Unit BJun 9, 2025$730,000Unit CJun 25, 2020$587,800Unit DAug 12, 2016$508,000Unit BMay 2, 2016$491,500Unit AOct 27, 2014$531,000Unit DAug 2, 2012$368,000Unit AAug 15, 2008$415,000Unit BJun 30, 2008$370,000Unit CMay 29, 2008$356,000Unit CAug 28, 2002$319,000

Values are TopHap estimates, not appraisals. Sales, ownership and tax figures come from recorded county documents via ATTOM and can lag by several weeks.

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.0.04
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

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%

All UnitsEvery property record the county has at this street address, such as the units in a condo building. Prices shown are our estimates, not asking prices.

21 Main St
2 bd · 1 ba · 951 ft²
$757K
21 Main St # B
1 bd · 1 ba · 683 ft²
$768K
21 Main St # C
1 bd · 1 ba · 679 ft²
$786K
21 Main St # D
1 bd · 1 ba · 683 ft²
$758K
21 Main St Apt E
2 bd · 2 ba · 1,608 ft²
$1.4M

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

About 21 Main St

How many units are in 21 Main St, Charlestown, MA?

21 Main St, Charlestown, MA has 5 residential units across built in 1987, according to county assessor records.

What is a unit at 21 Main St, Charlestown, MA worth?

The median TopHap Estimate across the 5 units at 21 Main St, Charlestown, MA is $767,887. That works out to $1110 per square foot. Units run from 679 to 1,608 square feet. Estimates are modelled from recorded sales and assessments, not appraisals.

Is 21 Main St, Charlestown, MA expensive for Charlestown?

Units at 21 Main St, Charlestown, MA carry a median of $1110 per square foot, 35% above the Charlestown median of $821 per square foot.

How often do units sell at 21 Main St, Charlestown, MA?

0 units at 21 Main St, Charlestown, MA sold in the last 12 months, out of 26 recorded arms-length sales all time. That is a turnover rate of 0.0% of the building per year.

Have units at 21 Main St, Charlestown, MA appreciated?

Across 19 repeat sales of the same unit, 21 Main St, Charlestown, MA returned a median 4.2% per year. Because each pair is the same unit bought and sold, the figure is not distorted by which units traded. The median owner held for 7.0 years.

What floor plans does 21 Main St, Charlestown, MA have?

The most common plan at 21 Main St, Charlestown, MA is a 1-bedroom of 683 square feet, repeated 2 times, with a median estimate of $762,996. TopHap identifies 1 recurring plans in the building.

More homes on Main St Apt E

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Assigned schools

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