100 William Street, Manhattan
Commercial · built 1973 · Block 68, Lot 36.
Building permits
- Alteration, filed Jun 3, 2026, estimated cost $190K, described as “Temporary sprinkler system for existing 21 building as per NYC bc 2022, fc 2022, nfpa 13 2016 all as amended by NYC bc 2022 appendix q.”
- Major Renovation — Conversion, filed Mar 3, 2026, estimated cost $88.8M, 427 units added, 24 stories, described as “Conversion from office (b) occupancy to residential (r-2) occupancy pursuant to article i, chapter v of the NYC zoning resolution and article 7B of the nys multiple dwelling law for residential conversion.”
- Alteration, filed Feb 13, 2026, estimated cost $1.5M, described as “Removal and disposal of existing windows at floor 3-21; alterations propose no change to use, occupancy, or structural stability.”
- Alteration, filed Dec 23, 2025, estimated cost $10.0M, described as “Proposed interior demolition of existing non-structural interior partitions of existing office building as per plan. No change of use, egress and occupancy.”
- Alteration, filed Jul 1, 2025, estimated cost $30K, described as “Removal and installation of non-loadbearing partitions and associated finishes. No change to egress, use, or occupancy.”
- Alteration, filed Nov 26, 2024, estimated cost $38K, described as “Installation of 1 new booster pump on roof and associated piping on 20C/21M thru roof as indicated on plans. No change in use, egress or occupancy.”
- Alteration, filed Jun 26, 2024, described as “IRA to assist with Condition Assessment.”
- Alteration, filed May 24, 2024, described as “Added Additional Suspended Scaffold Installation For Facade Restoration And Inspection”
- Alteration, filed May 21, 2024, estimated cost $397K, described as “Interior renovaton to corridor, restrooms and elevator lobby (21M/20C nycds), work to include non load bearing partitions, flooring, ceiling, door modifications and related construction as per plans filed herewith. No change in use, egree…”
- Alteration, filed May 9, 2024, estimated cost $1K, described as “Installation of temporary heavy duty sidewalk shed as per plans. No change in use, egress or occupancy. Sidewalk shed shall comply with chapter #33 of 2022 the NYC building code. Live load 300PSF.”
- Alteration, filed May 8, 2024, estimated cost $1.0M, described as “Interior renovaton to (21M/20C nycds) to non load bearing partitions, flooring, ceiling, door modifications and related construction as per plans filed herewith. No change in use, egree or occupancy.”
- Alteration, filed Mar 11, 2024, estimated cost $8K, described as “Office renovation work (ste 1205) to include partition, ceiling and door work as indicated on plans. No change in use, egress or occupancy.”
- Alteration, filed Nov 15, 2023, estimated cost $2.0M, described as “Facade restoration and installation of guardrails at upper roof level as indicated on plans. No change in use, egress or occupancy.”
- Alteration, filed May 24, 2023, estimated cost $103K, described as “Demo/white box in ste 2100 21M/20C mechanical work includes removals of ac units and associated duct and piping as well removal of generator on roof as indicated on plans. No change in use, egress or occupancy.”
- Alteration, filed May 24, 2023, estimated cost $105K, described as “Removal of 30,000 gallon fuel storage tank in cellar and existing fuel oil pipng to generator to be abandoned and removed on roof as indicated on plans. No change in use or occupancy.”
- Alteration, filed May 24, 2023, estimated cost $65K, described as “Demo/whitebox of ste 2100 21M/20C - work to include sprinkler head removals, removal of pre-action system, installation of temp loop and removal of 2 fire hose cabinets as indicated on plans. No change in use, egress or occupancy.”
- Alteration, filed Mar 22, 2023, estimated cost $2.0M, described as “Demolition and white box of ste 2100 21M/20C - work to include removal of non-load bearing partitions, ceiling and doors as indicated on plans. No change in use, egress or occupancy.”
- Alteration, filed Jan 27, 2023, estimated cost $793K, described as “Office renovation (ste - 750 - mfj ) work to include partition, ceiling , and door modifications as indicated on plans. No change in use, egress or occupancy.”
- Alteration, filed Jan 20, 2023, estimated cost $25K, described as “Sprinkler modifications (Ste - 750 - MFJ) as indicated on plans. No change in use egress or occupancy.”
- Alteration, filed Jan 20, 2023, estimated cost $80K, described as “Mechanical modifications (ste - 750 - mfj) as indicated on plans. No change in use, egress or occupancy.”
- Alteration, filed Oct 26, 2022, estimated cost $140K, described as “Mechanical modifications (Suite 1701 - 16C/17M) as indicated on plans filed herewith. No change in use, egress or occupancy.”
- Alteration, filed Oct 25, 2022, estimated cost $5K, described as “Plumbing modifications (Suite 1701 16c/17m) as indicated on plans. No change in use egress or occupancy.”
- Alteration, filed Oct 25, 2022, estimated cost $25K, described as “Sprinkler modifications (Suite 1701 - 16c/17m) as indicated on plans. No change in use egress or occupancy.”
- Alteration, filed Sep 22, 2022, estimated cost $1.2M, described as “Interior renovations (suite 1701 17M/16C) work to include partition, ceiling and door modifications as per plans. No change in use, egress or occupancy”
- Alteration, filed Apr 1, 2022, estimated cost $35K, described as “Interior renovations (goyareb suite 1820) work to include partition, ceiling and door modifications as per plans. No change in use, egress or occupancy”
18 more, older permits are in this building’s full list on the map.
Property taxes
- Assessment
- $46,323,000
- 2026–27 tax
- $4,624,086
- Market value (city estimate)
- $102,940,000
- Taxable value
- $42,626,164
- Assessed land
- $10,845,000
- Assessed improvements
- $35,478,000
Zoning
C5-5: floor area ratio 20.37 built, above the 15.00 base zoning allows, which bonuses, transfers or older rules can permit.
Flood zone
Current FEMA flood map: zone X, minimal flood hazard.
Recent sales
- Dec 12, 2025: $70,000,000
Open-market sales since 2016, from the Department of Finance’s sales files.
Board and land use applications
- 100 WILLIAM ST (City Planning P2010M0010): Completed, decided Nov 16, 2010. MINOR MOD THE SPECIAL PERMIT FOR IMPROVEMENTS TO THE PLAZA*(POPS)