National Green
City Day
Founded by Mio Reggio creator Monica Tierney, National Green City Day has been recognized through official proclamations in cities including Seattle, Washington, DC, Portland, and San Diego.
A Global Shift
A global shift toward greener cities is already underway.
Buildings are adapting. Materials are changing. Urban spaces are being rethought.
Across the world, new approaches are reshaping how cities function and feel — offering new ways for nature, people, and living systems to coexist.
National Green City Day highlights and shares these evolving approaches, creating space for communities to engage with them in meaningful ways.
What It Is
National Green City Day, celebrated on October 1st, brings together cities, schools, and communities to explore how nature can be integrated into the built environment.
It celebrates and shares emerging approaches from around the world, while also asking a fundamental question:
What if cities were designed with children, nature, and wellbeing in mind?
Nature In The Built Environment
Cities are rethinking how nature is integrated into everyday environments:
Vertical Forests
Vertical forests rising within dense urban skylines
Living surfaces
Living surfaces, including moss walls and regenerative materials
Sidewalk
Sidewalk pocket parks and micro-ecosystems woven into overlooked spaces
Green roof
Green roof bus stops and small-scale interventions embedded into daily life
Biodiversity features
Biodiversity features integrated into the built environment
These approaches are becoming part of how cities function, not separate from them.
Children As Co-creators
While these approaches are reshaping cities, children are rarely included in how these environments are imagined and experienced.
National Green City Day brings their perspective into the center — not only as users of these spaces, but as contributors to how they evolve.
Through play, observation, and curiosity, children offer a way of seeing the city that is essential to creating more connected, livable urban environments.
A Broader Vision
National Green City Day exists within a broader global shift toward more integrated, livable urban environments.
At its core is a growing exploration of how nature, living systems, and people can coexist more meaningfully within cities.
Within this, children offer a unique perspective — engaging with the natural world through play, observation, and design.
This extends across educational environments, product design, and emerging media concepts focused on early childhood and environmental awareness.
From Play To Practice
At Mio Reggio, children build understanding through direct engagement with their environment.
Through play, exploration, and observation, they begin to imagine how cities can be shaped — not just for people, but for nature and living systems as well.
