BTC City Ljubljana, a significant retail park in Slovenia, is an experimentation site in the Desire project. BTC, in collaboration with the CER-Sustainable Business Network, worked on experimenting with urban greening, biodiversity, and climate change adaptation. The project engages diverse stakeholders, including businesses, academia, and the local community, to co-create a sustainability strategy for BTC City 2025–2030. Key activities run under Desire include workshops, hackathons, and exhibitions, which foster collaboration and generate innovative solutions such as reducing carbon emissions and enhancing green spaces to combat the urban heat island effect in line with current EU policies. This chapter shows how the experimentation also implements concrete measures, including planting trees and developing green corridors to improve microclimate and biodiversity. Through its Green Star Sustainability Certification and a strong emphasis on stakeholder engagement, BTC City builds a collaborative network for its green transformation. The Desire project demonstrates how systemic collaboration, clear leadership, and community empowerment can drive meaningful environmental change, positioning BTC City Ljubljana at the forefront for the transition to urban sustainability.