Landmark: Park Slope Historic District Extension II: Historic District. Regulation type: Certificate of No Effect. Work types: Filing any work, Occupiable rooftop addition: Buildings in a historic district, Interior Alterations, No underpinning, Construct patio, retaining wall, berm, in-ground pool or other landscape feature, Primary Facades: Existing original/historic openings at small residential and commercial buildings, New or modified openings at visible secondary facades, Existing openings at visible secondary facades, Repointing mortar joints, Repair of natural and cast stone, Filling in existing openings at nonvisible or minimally visible secondary facades, Primary Facades: Existing non-original/non-historic openings at small residential and commercial buildings, Rear yard decks, Alteration, Restoration and Maintenance of existing fire escape, Rail lifts, Lighting fixtures and intercom panels, Through-wall HVAC equipment on primary facades. Address: 121 AND 123 6TH AVENUE. Community Board: BK-06. Issued: 2021-09-23. Expires: 2025-09-23. Applicant: Richard Goodstein. Owner: Robert Saffayeh.