Block Hall, 21 South William Street, #6B

RLS IDX Data display by CityRealty.com, LLC. This information is not verified for authenticity or accuracy and is not guaranteed and may not reflect all real estate activity in the market. ©2026 The Real Estate Board of New York, Inc., All rights reserved. IDX information is provided exclusively for consumers’ personal, non-commercial use and it may not be used for any purpose other than to identify prospective properties consumers may be interested in purchasing.

All information furnished regarding property for sale, rental or financing is from sources deemed reliable, but no warranty or representation is made as to the accuracy thereof and same is submitted subject to errors, omissions, change of price, rental or other conditions, prior sale, lease or financing or withdrawal without notice. All dimensions are approximate. For exact dimensions, you must hire your own architect or engineer and for no listing shall the number of bedrooms listed be considered a legal conclusion.

All closed sales data has been provided by the New York City Department of Finance via the Automated City Register Information System (ACRIS). No warranty or representation is made as to the accuracy of any data provided by ACRIS or any other sources.

CityRealty is committed to ensuring digital accessibility for individuals with disabilities. We are continuously working to improve the accessibility of our web experience for everyone, and we welcome feedback and accommodation requests. If you wish to report an issue or seek an accommodation, please contact us at accessibility@cityrealty.com.