The global Her City initiative provides a framework for gender-sensitive urban planning, which seeks to create inclusive and accessible public spaces that meet the needs of all residents, particularly women and girls, who have often been overlooked in traditional urban design. This paper presents the results of Germany's first Her City initiative in Weimar— a city rich in cultural heritage with a vibrant tourism sector that strongly influences its public spaces. It contributes to existing studies in this field by providing an innovative methodological analysis of Weimar’s public spaces through gender-sensitive, data-driven, and participatory processes, with the aim of identifying strategies for improvement. The Her City Toolbox was utilised and extended through a participatory citizen science approach with 18 young women and the collection of gender-sensitive data regarding public space usage. Data collected from two city walks, three workshops, open space assessments as well as measurements of people’s movements and stationary activities were triangulated to reveal five thematic fields that highlight how public spaces are failing to meet the needs of women and girls. These include (1) Facilities & Furnishing, (2) Representation & Appreciation, (3) Security & Social Control, (4) Mobility & Accessibility, and (5) Visibility & Appropriation. Collaborations with local stakeholders combined with communication platforms and media contributed significantly to the project’s impact. The paper concludes by emphasising the necessity of adopting a gender-sensitive, participatory, and data-driven approach to urban planning to address the diverse needs of all city dwellers.