This presentation reflects on lessons learned from the Thames Tideway Tunnel, focusing on how major infrastructure projects can create lasting value for host communities. Through a case study with a Deptford primary school, he explores principles of successful co-design, including transparency, clear roles, genuine participation, shared learning, and long-term legacy. The experience demonstrated that public realm projects are most successful when communities help shape them, inspiring future skills development, mentoring, apprenticeships, and lasting social impact.