Want · Office
Series B fintech needs 8,000 to 12,000 SF
Posted by the tenant · Fintech
- Where
- Midtown South, Flatiron +1
- Size
- 8,000 to 12,000 SF
- Budget
- to $85/SF
- Move in
- Jan 2027
Near subwayHigh ceilings
Owners: got a fit?I have a fit
Commercial condominium · Flatiron, Manhattan
Alexander Building
636 Avenue of the Americas, New York, NY 10011
The Alexander Building (636 Avenue of the Americas) is a 7-floor commercial condominium in Flatiron, Manhattan, built in 1896, with about 56,000 square feet of office space according to city records.
Also at 634-640 Avenue of the Americas and 57-69 West 19th Street.
- Office space
- 56K SF
- Floors
- 7
- Year built
- 1896
- Zoning
- C6-2A
The 69th largest of the 75 office buildings we track in Flatiron. Compare it with 6 neighbors
No space at 636 Avenue of the Americas is listed on Leasemark yet. Own or broker space here? List it free and it is matched against every active requirement the day it goes up, or import a spreadsheet of up to 50 spaces at once.
Compared with its neighbors
How the Alexander Building compares
Next to the 6 nearest large office buildings, all within a 1 minute walk, the Alexander Building is the smallest by office floor area. It went up in 1896; the median neighbor dates from 1902. Its estimated property tax, about $21.83 a square foot of floor area before abatements, is below the neighbors' median of $24.27.
| Building | Office space | Floors | Built | Tax / SF | Last sale |
|---|---|---|---|---|---|
| Alexander Building, 636 Avenue of the Americas | 56K SF | 7 | 1896 | $21.83 | n/a |
| Crystal Building, 40 West 20th Street | 95K SF | 12 | 1910 | Exempt | n/a |
| 39 West 19th Street | 98K SF | 12 | 1910 | $11.77 | n/a |
| 620 Avenue of the Americas | 211K SF | 7 | 1900 | $18.60 | n/a |
| Simpson, Crawford & Simpson Building, 635 Avenue of the Americas | 57K SF | 8 | 1902 | $33.91 | Jun 2021, $121M |
| Simpson, Crawford & Simpson Building, 641 Avenue of the Americas | 122K SF | 8 | 1902 | $24.27 | Jun 2021, $204M |
| 615 Avenue of the Americas | 77K SF | 5 | 1877 | $31.33 | n/a |
Sources: NYC Department of City Planning, PLUTO 26v2 for size, floors and year built; NYC Department of Finance 2026/27 roll for tax (taxable value times the class rate, before abatements, over the whole floor area); ACRIS for the last deed that moved the whole lot for a real price (a price for several lots is their combined price; condominiums sell by the unit and show n/a). Large means at least 50,000 SF of the building's main use. Walking times are straight-line estimates.
NYC tax lot records
Building facts
- Building name
- Alexander Building
- Other addresses
- 634-640 Avenue of the Americas; 57-69 West 19th Street
- ZIP code
- 10011
- Building type
- Commercial condominium (city class RC)
- Total floor area
- 73,270 SF
- Commercial floor area
- 73,270 SF
- Office
- 55,707 SF
- Retail
- 17,563 SF
- Height
- 7 floors
- Average floor
- About 10,500 SF (floor area divided by floors)
- Year built
- 1896
- Lot area
- 10,750 SF
- Zoning district
- C6-2A
- Built FAR
- 6.82
- Max commercial FAR
- 6
- Historic district
- Ladies' Mile Historic District
- Tax lot (BBL)
- 1008217506
Source: NYC Department of City Planning, PLUTO 26v2, pulled 2026-09-30; addresses from the Property Address Directory (PAD) 26b; building name from the NYC Landmarks Preservation Commission (below); subway stations from the MTA Subway Stations dataset, pulled 2026-10-02. Floor areas are the city's estimates for the whole building, not available space. Walking times are straight-line estimates. How we build these pages. Something wrong on this page? Tell us.
NYC Department of Finance records
Owner, property tax and assessed value
The Alexander Building is a condominium of 2 tax lots. NY HOTEL TRADES CNCL/HOTEL ASSOC NYC/HLT H CNTR INC, one of 2 owners of record on the roll, owns the units that make up 62% of its market value. For tax year 2026/27 the city values the Alexander Building at $35 million and assesses it at $15.8 million. After phase-ins and exemptions its taxable value is $14.7 million; at the Class 4 rate of 10.848% (tax year 2025/26, the latest rate the Department of Finance lists) that comes to about $1.6 million a year before abatements, roughly $21.83 per square foot of floor area. Commercial leases here often pass a tenant's share of tax increases over a base year through as additional rent.
- Largest unit owner
- NY HOTEL TRADES CNCL/HOTEL ASSOC NYC/HLT H CNTR INC (62% of market value)
- Tax class
- Class 4 (commercial and industrial)
- City market value
- $35,041,000
- Land market value
- $3,500,000
- Assessed value
- $15,768,450
- Taxable value (phased in)
- $14,742,540
- Estimated yearly tax
- About $1.6 million
- Tax per SF of floor area
- About $21.83
- Condominium tax lots
- 2
- Owners of record
- 2
City market value by tax year
Source: NYC Department of Finance, Property Valuation and Assessment Data (2026/27 roll, summed over 2 condominium tax lots; owner names as the roll records them, which cuts some long names short), pulled 2026-10-02; tax rate from the Department of Finance tax rates page, checked 2026-09-28. The estimate is the taxable value times the class rate. It leaves out abatements, payment-in-lieu-of-taxes agreements and charges, so the actual bill can differ.
NYC Department of Buildings permits
Work permits and build-outs
In the 12 months to September 2026, the Department of Buildings issued first permits for 1 job at the Alexander Building. In the last two years, interior work was permitted on 6 floors (floors 1 to 6, the cellar and the mezzanine). The newest build-out, on floors 1 to 6, the cellar, the mezzanine and the roof, was first permitted in September 2025 (plumbing, sprinklers, standpipe; filed cost estimate $285,000).
- New jobs, last 12 months
- 1
- Initial permits, last 12 months
- 6
- Newest job first permitted
- November 2025
- Interior build-outs, last 24 months
- 3
- Floors with interior work, last 24 months
- 1 to 6, cellar, mezzanine
- Facade and sidewalk jobs, last 24 months
- 2
Recent build-outs
New jobs by year
Build-outs across FlatironWhere NYC offices are being built out
Source: NYC Department of Buildings, DOB NOW: Build Approved Permits, pulled 2026-10-02 (permits issued through 2026-09-30). A job counts once, when its first permit is issued; renewals are not new work. A build-out groups jobs on the same floors first permitted within 120 days of each other. Costs are the estimates filed with the jobs. Jobs filed before DOB NOW (in the older BIS system) are not counted. A permit is approval to do the work; it does not say who the work is for or whether it is finished.
Landmarks Preservation Commission records
Architecture and history
The Alexander Building was designed by Buchman & Deisler and built in 1896 in the neo-Renaissance style. It stands in the Ladies' Mile Historic District, so exterior changes and new signage go through the Landmarks Preservation Commission.
- Architect
- Buchman & Deisler
- Constructed
- 1896
- Style
- neo-Renaissance
- Primary material
- Brick
- Built as
- Store
Source: NYC Landmarks Preservation Commission, Individual Landmark and Historic District Building Database on NYC Open Data, pulled 2026-10-02. A designation can cover part of a lot, such as a facade or a lobby interior.
Office space nearby in Flatiron
Nothing is listed nearby yet. The labeled examples below show how a space appears; they are not on the market.
What a requirement here looks like
No live requirements for office space in Flatiron yet. These labeled examples show what tenants post. List a space in 636 Avenue of the Americas and we match it against every new one automatically.
Want · Office
Startup seeking furnished sublease
Posted by the tenant · Software
- Where
- Flatiron, Midtown South +1
- Size
- 6,000 to 11,000 SF
- Budget
- to $60/SF
- Move in
- Nov 2026
Furnished
Owners: got a fit?I have a fit
Before you sign
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Questions about Alexander Building
How big is the Alexander Building?
The Alexander Building has about 73,000 square feet of floor area in total, including 56,000 square feet of office and 18,000 square feet of retail, according to NYC PLUTO 26v2. These are the city's estimates for the whole building, not space that is available.
When was the Alexander Building built?
The Landmarks Preservation Commission's building records date the Alexander Building to 1896, designed by Buchman & Deisler. The building is 7 floors tall.
Who designed the Alexander Building?
Buchman & Deisler, according to the Landmarks Preservation Commission's building records, which list the style as neo-Renaissance and its original use as a store.
What is the address of the Alexander Building?
The Alexander Building is at 636 Avenue of the Americas in Flatiron, Manhattan. City records list 634-640 Avenue of the Americas and 57-69 West 19th Street on the same tax lot (BBL 1008217506). A space listed on Leasemark at any of these addresses shows up on this page.
What is the ZIP code of 636 Avenue of the Americas?
636 Avenue of the Americas is in ZIP code 10011, according to the city's tax lot records (NYC PLUTO 26v2) and the Department of Finance's assessment roll. The Alexander Building is at 636 Avenue of the Americas, New York, NY 10011, in Flatiron.
What is the zoning at the Alexander Building?
The lot is in the C6-2A zoning district. PLUTO lists a built floor area ratio (FAR) of 6.82 and a maximum commercial FAR of 6 for this lot. It is inside the Ladies' Mile Historic District, so exterior changes go through the Landmarks Preservation Commission.
What subway station is closest to the Alexander Building?
The closest subway station to the Alexander Building is 23 St (the F and M trains), about 950 feet away in a straight line, roughly 4 minutes on foot. Also nearby: 14 St (the 1, 2, 3, F, M and L trains, connected to 6 Av), 4 min walk; 18 St (the 1 train), 4 min walk. Walking times are straight-line estimates; the street route is longer.
Who owns the Alexander Building?
The Alexander Building is a condominium of 2 tax lots. NY HOTEL TRADES CNCL/HOTEL ASSOC NYC/HLT H CNTR INC, one of 2 owners of record on the roll, owns the units that make up 62% of its market value. That is from the NYC Department of Finance's 2026/27 assessment roll (BBL 1008217506). Deeds and mortgages for each unit are public in ACRIS, the city's property records system.
Is there construction at the Alexander Building?
In the 12 months to September 2026, the Department of Buildings issued first permits for 1 job at the Alexander Building. In the last two years, interior work was permitted on 6 floors (floors 1 to 6, the cellar and the mezzanine). The newest build-out, on floors 1 to 6, the cellar, the mezzanine and the roof, was first permitted in September 2025 (plumbing, sprinklers, standpipe; filed cost estimate $285,000). These are the Department of Buildings' DOB NOW work permits for tax lot 1008217506. A permit is approval to do the work; it does not say who the work is for or whether it is finished.
What are the property taxes at the Alexander Building?
The Department of Finance's 2026/27 assessment roll lists a taxable value of $14.7 million for the Alexander Building (the sum of its 2 condominium tax lots). At the Class 4 rate of 10.848% (tax year 2025/26, the latest rate the Department of Finance lists), that is about $1.6 million a year, roughly $21.83 per square foot of floor area, before abatements such as ICAP. The city's property tax records for BBL 1008217506 show the actual bill.
What is the assessed value of the Alexander Building?
For tax year 2026/27, the NYC Department of Finance puts the market value of the Alexander Building at $35 million ($3.5 million of it land) and its assessed value at $15.8 million, the 45% of market value the city assesses for Class 4 property. The city's market value rose 19% from 2022/23 ($29.5 million) to 2026/27.
Is there office space for lease at the Alexander Building?
No space at 636 Avenue of the Americas is listed on Leasemark right now. Owners and brokers can list space here for free, and tenants can post a requirement to be matched when space opens up.
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