321 Union Street
321 Union Street, between Court and Smith streets, Carroll Gardens
BBL 3004287503 · BIN 3391752
- Type
- Condominium
- Landmark
- No
- Amenities
- Private gardens and roof terraces in selected homes; central air and in-unit laundry
Every recorded sale at this building, 2006–2025
Price-per-square-foot over time, the line- and floor-premium curves, and every recorded sale.
- Median $/sf
- $1,567
- Listing discount
- -1.6%
- Recorded sales
- 19
- On record
- 2006–2025
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A Private Pricing Opinion — what your apartment at 321 Union Street would likely sell for today, what it costs to sell, and what you’d walk away with — reviewed personally against condition, exposures, renovation quality, and the competition actually on the market.
About the building
321 Union Street is a brownstone conversion by architect and developer Alex Barrett. The project retained walk-up access within the four-story structure. Its eight-home offering was accepted in December 2006, original sales closed the following year, and DOB signed off the alteration in September 2008. Seven residences occupy the building today, including a large floor-through home.
The residential mix includes smaller one-bedroom homes, two-bedroom apartments and a larger full-floor home. Garden duplexes place their principal bedrooms on the main level and add recreation space below, with private rear yards reached from the residential plan. Upper duplexes open to substantial roof terraces, including a wraparound configuration. Interior living areas range from about 690 square feet in the smaller homes to roughly 1,800 in the full-floor layout. Renovated apartments have central cooling and in-unit laundry.
Recent sales
Recent closings at this building, curated by The Roebling Team research desk. Prices are the transfer amounts recorded with the NYC Department of Finance; apartment-level detail is checked against the building’s own file in The Roebling Research Library before publishing.
| Date | Unit | Apartment | Price | PPSF | vs. Ask |
|---|---|---|---|---|---|
| Feb 9, 2023 | 4A | 2 BR · 2 BA · 1,061 sf | $1,663,000 | $1,567/sf | off-mkt |
| Dec 4, 2020 | 1A | 2 BR · 2 BA · 1,082 sf | $1,165,000 | $1,077/sf | -10.3% |
| Aug 22, 2019 | 2 | 3 BR · 3 BA · 1,787 sf | $2,695,000 | $1,508/sf | +0.0% |
| May 15, 2019 | 3B | 2 BR · 2 BA · 1,192 sf | $1,527,000 | $1,281/sf | +5.3% |
| Apr 2, 2014 | 3A | 1 BR · 1 BA · 690 sf | $760,000 | $1,101/sf | +1.5% |
| May 14, 2012 | 1B | 2 BR · 1,292 sf | $1,085,000 | $840/sf | -3.6% |
| Jul 26, 2011 | 4B | 3 BR · 1,459 sf | $1,501,000 | $1,029/sf | +15.9% |
| Dec 21, 2007 | 1B | 2 BR · 1,292 sf | $1,100,000 | $851/sf | +0.0% |
Market read. $/sf is measured on the latest sales with reliable square footage (2023): a median $1,567/sf across 1 sale. The building has traded as recently as 2025. Median listing discount -1.6% over ask.
The retrade record
Lines that have traded more than once in the public record — the building’s appreciation arc, apartment by apartment.
Full closing history with price-per-square-foot over time, the complete retrade record, and every line that has traded.
Sales sourced from NYC Department of Finance recorded transfers (BBL 3-00428-7503) and verified listing data. Apartment-level facts (line, condition, asking-price context) curated and cross-verified by The Roebling Team research desk. Not all transactions cross-verify with ACRIS records — sponsor and LLC purchases sometimes record at stipulated values rather than market price; square footage from recorded condo declarations and offering plans.
Buying here? Condo closing costs with a mortgage typically run 3 to 6% of the price. See NYC co-op and condo closing costs, line by line.
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What to know if you’re buying
The former 421-a benefit has ended. Older advertisements showing reduced taxes are therefore a poor measure of current carrying costs at this condominium; the post-expiration bill is the relevant comparison.
Comparable buildings
- 47 Dean Street — A small modern condominium with two apartments per floor.
- 361 Clinton Street — A low-rise condominium with a larger ownership base and an earlier construction date.
- 344 Degraw Street — A larger nearby condominium with a more substantial shared building structure.
More Carroll Gardens buildings
- 241 Carroll Street — 2014 condominium
- 280 Sackett Street — 1930 condominium
- 316 Carroll Street — condominium
- 331 Sackett Street — 1920 co-op
- 339 Sackett Street — 1986 co-op
- 344 Degraw Street — 2000 condominium
The neighborhood
For the full neighborhood — its buildings, character, and market — read The Roebling Team Guide to Carroll Gardens.
How to read the facts on this page. Items attributed to an offering plan describe the building as it was offered at that filing — unit mix, square footage, the amenity program as planned. They are not a statement about how the building operates today. Tax and compliance figures are sourced separately to current City records and carry their own dates. House rules, staffing and fee policy can change by board resolution without any public filing: treat every policy line here as a starting point for diligence and confirm it with the managing agent. Where this page compares one building or neighborhood to another, that is our analysis of the recorded record — it names the measure, the period and the sample it rests on, and it is an observation about medians rather than a prediction about any particular apartment.
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