Urban (main city)

The Ciénaga de las Quintas is a coastal wetland located alongside one of Cartagena’s main roads, adjacent to the public market square and situated between the Jiménez and Bazurto Bridges. It is home to two predominant mangrove species (Ref 1). The wetland currently faces pollution problems because it is used for the disposal of solid waste, such as plastics and construction materials, and it receives wastewater and household garbage from nearby residences. Las Quintas is also the main waste disposal area for the Bazurto market, which handles 43,430 tons of food products each month (ref 3). The recovery initiatives for the Ciénaga de las Quintas are led by the Environmental Public Establishment of Cartagena (EPA Cartagena) in collaboration with other public institutions, the private sector, and citizens, with the main goal of achieving the ecological restoration of the city's water bodies and to maintain and preserve our mangrove ecosystems (ref 2). Since 2020, key implementation activities have included the removal of solid waste, planting of native tree species, dismantling of informal structures within the mangrove zone, and the rehabilitation of areas previously occupied by debris (Refs 4, 5).

Due to rapid urbanization and development, cities in China, including Kunming, face challenges in managing neglected urban spaces, particularly vacated demolition sites and leftover land (Ref 1, 2, 3). To address this issue and enhance residents' well-being, Kunming has created 400 pocket parks since 2022, transforming forgotten corners into vibrant green spaces (Ref 4, 5).
One of these parks, Wenxing Pocket Park in Xishan District, was built in 2023 on 2.3 hectares of land (Ref 6). Located next to a secondary school and two protected historical relics, the park not only preserves historical heritage but also reflects cultural value (Ref 6, 7). In addition to increasing urban green spaces, the park provides recreational and physical facilities for residents, children, and students (Ref 6). Its design is inspired by traditional architectural styles and incorporates wood craftsmanship, as well as ecological sponge facilities (Ref 6, 7).
The park also features science gardens, promoting awareness and knowledge of herbs and sustainability (Ref 6). The project employs methods such as infiltration, stagnation, storage, purification, and drainage to manage rainwater effectively. By utilizing the natural terrain, it creates ecological dry streams and sunken gardens that absorb and store rainwater, helping to control runoff. This approach aligns with the "sponge city" concept, promoting natural water accumulation, infiltration, and purification.
Additionally, the integration of various plants enhances the microclimate, supporting local wildlife and creating a healthy, vibrant public space. The Wenxing Pocket Park has been implemented by the Municipality of Xishan. (Ref.6,7)

The requalification project for Viale Buoncammino in Cagliari aims to revitalize the historic promenade while preserving its original layout and functions. Launched in September 2022 and completed in 2023, the project focused on enhancing the area’s aesthetic and environmental appeal. Key improvements include expanding green spaces by adding 560 new square meters, enhancing vegetation, and reducing surface runoff. This involves increasing permeable surfaces around existing trees to boost natural vegetation, improve bioclimatic comfort, and manage runoff during heavy rains.

The project also includes reconstructing pavements, optimizing seating areas, and repositioning urban furniture for better functionality and aesthetics. A modern LED lighting system will be installed to reduce energy consumption and operational costs, supporting the project's sustainability goals. The area is included between via Anfiteatro, viale Buoncammino and viale Giussani and also includes the squares F.Pilia and Marongiu-Pernis. The project aims to restore Viale Buoncammino as a dynamic social and cultural hub in Cagliari, appealing to both residents and visitors. (Refs. 1, 2, 3 & 4).

The Vera Park is a significant site in the city of Tbilisi, created in the mid-20th century. Located centrally, it is not only frequently visited by tourists but also used as a recreational area for the surrounding residents and workers (Ref. 1,2). The park is recognized as an immovable cultural heritage site, emphasizing its historical significance (Ref. 1). However, its condition had become quite desolate, necessitating extensive rehabilitation while preserving its original features (Ref. 2). Importantly, the project is carried out between the city of Tbilisi and the Asian Development Bank under the Livable Cities Investment Program (LCIP) to improve urban and tourism infrastructure (Ref. 1,2). As such, the project was developed through co-participatory planning, engaging citizens who have shown significant interest in the site’s development and will further serve as a precedent case for co-participatory planning in the future (Ref. 4,2).

The Urban Forestry Plan for Cartagena, led by EPA Cartagena, outlines a comprehensive strategy for enhancing the city's green infrastructure. The plan focuses on selecting suitable tree species, planting, and management to achieve several goals: reducing heat through shade, creating microclimates, protecting against climatic events such as coastal erosion and windstorms, enhancing food security, and enhancing the landscape's beauty. Over 10 years, the plan aims to establish at least 100,000 additional trees, increase overall tree cover, enhance accessibility to green spaces, and build a main ecological structure based on natural resources and biodiversity. It also emphasises the importance of local knowledge and resources (ref 1).
Formulated with community input, the plan commenced in 2013 and involved a detailed assessment of existing urban vegetation and climate conditions, utilising tools such as iTree. The development included international conferences and expert consultations to ensure a robust and informed approach (ref 1).

Liquid 3 is the first urban photo-bioreactor in Serbia, developed by an interdisciplinary team at the Institute for Multidisciplinary Research at the University of Belgrade (Ref. 1,2,3). Prompted by an appeal of the United Nations Development Programme (UNDP), the team was eager to find novel approaches to combat the city's severe air pollution issues while being space efficient and providing year-round benefits (Ref. 3). The key to the bioreactor are algae which are very efficient in sequestering carbon and filtering heavy metals from the air (Ref. 2). A Liquid 3 feature can be quickly set and occupies a plot of only 3 m². Some of its benefits include its ability to withstand high levels of air pollution and its ease of installation on surfaces like walkways and other sealed infrastructure (Ref. 2,3). Additionally, by design, Liquid 3 integrates amenities such as power outlets, a bench, and nighttime lighting (Ref. 1). The selected strain of algae can tolerate temperatures between 5-35°C making it deployable all year. However, monthly maintenance is required, during which the water and algae are replaced—both of which can be repurposed, for example, as fertilizers (Ref. 6).The project has received global media coverage as well as a prize for the best innovative and climate-smart solution in Serbia. Its success has prompted the installation of two more such bioreactors in Serbia, with interest coming from other countries such as Hungary and the UAE (Ref. 1,4).

In 2022, the municipality of Cagliari launched a project to revitalize Viale Trieste, one of its avenues, by redesigning its roads and pedestrian areas and adding new green spaces. The project covers approximately 1,300 meters and 36,500 square meters, and will be completed in two phases, each focusing on different sections of the avenue. With a budget of 12 million euros, funded by municipal, national, and EU resources, the aim is to transform Viale Trieste into a vibrant, accessible, and attractive space for everyone.

The renewal will introduce new green spaces and improved drainage systems to enhance soil permeability. As part of this, some trees will be relocated to other areas of the city to address root issues and improve survival rates. Dead or unstable ficus trees will be removed, while 79 new trees will be planted. Older ficus trees will be relocated to city parks, with younger ones planted along the avenue to prevent pavement damage and promote sustainability. The project also includes upgrading water supply and drainage systems to manage stormwater more effectively, reducing the risk of flooding and improving sustainability. Public lighting will be modernized, with new street lamps and dedicated lighting for pedestrian and bicycle paths to make the area safer and more welcoming after dark.

However, the community has expressed concerns about the project, citing safety issues, delays, disruptions, and poor communication from officials. There is also significant opposition to replacing the historic ficus trees, valued for their environmental and historical significance, with Chinese pear trees and younger ficus (Refs. 1, 2, 3, 4, 5, 6, 11, 16).

The Parque Lineal de Crespo in Cartagena, Colombia, is an urban green space built in 2016-2017 that had fallen into neglect (ref 4) and recently has undergone revitalization initiatives (ref 2). Announced in January 2024 by the Mayor of Cartagena, Dumek Turbay Paz, the project aims to reclaim and enhance this public park as a hub for recreation and community activities, fostering urban well-being and environmental stewardship​ (ref 2 and 3). The local government spearheads the intervention, and the Instituto Distrital de Deporte y Recreación (IDER) has been tasked with the park's management, ensuring its upkeep and the development of activities. The project was launched following an inspection by the Mayor and other local officials, who underscored the need for better infrastructure, safety, lighting, and green coverage through tree planting ​(ref 2 and 3). The primary objectives of the Parque Lineal de Crespo project include revitalising the park through enhanced maintenance, security, and the introduction of recreational and sports facilities. The project also aims to relocate weekend recreational activities, such as a popular bike path (ciclovía), from the congested Avenida Santander to the park, thereby reducing traffic disruptions and enhancing safety ​(ref 2 and 3). The park is relevant for the city because it combats coastal erosion caused by the rising Caribbean waters (Ref 1). The Park aims to be an icon of culture and recreation (ref 1). The project inspired a neighbours initiative, the Friends of the Crespo Linear Park, are a non-profit organization whose objective is to collaborate in the conservation of the Park by contributing awareness initiatives to the population, alerting authorities, and developing new ways to interact with the environment, such as guided bird watching activities and sports (ref 1).

In the city of Ciudad Juárez, the municipality, in collaboration with UN-Habitat, aims to design and create a park that encompasses the yards and unmaintained areas surrounding the railway station, transforming these spaces into an accessible and safe public area. This project covers over 500,000 square meters and addresses not only degraded areas but also several public squares. Described as "a coordinated urban recycling strategy," this initiative seeks to repurpose existing public squares and rehabilitate neglected spaces into vibrant green areas that feature universal accessibility, native vegetation, and urban furniture designed to enhance safety. The project also aims to provide increased recreational opportunities, improve permeability, and introduce additional shaded areas. A key component of improving permeability involves the restoration and incorporation of acequias—traditional historical irrigation systems that absorb and manage excess rainwater, thereby reducing the likelihood of flash floods.
Additionally, the project focuses on the restoration and promotion of significant historical buildings, such as the old railway station and the whiskey factory, integrating them into a larger cultural and sports facility area at the municipal scale. The overarching goal is to revitalize the site through effective coordination with the relevant authorities responsible for the spaces adjacent to the railway station, stretching from Plaza Misión de Guadalupe to Blvd. Municipio Libre. This collaborative effort aims to accommodate both sports and cultural facilities while also creating a green corridor.
Furthermore, the project intends to reforest, redesign, and enhance Plaza Misión de Guadalupe, Plaza Monumento a Benito Juárez, and other residual public spaces and gardens. This initiative aligns with its Public Space Strategy, which emphasizes the development of gender-inclusive and resilient public spaces.(Ref 1, 3, 4).

An old park in Gothenburg was renovated to become "the world's best park when it rains" and attract visitors all year round. Rainfall is common in Gothenburg, but more importantly, the amount and intensity of rain are expected to increase in the future due to climate change. Municipal real estate company Higab had the park renovated to make the entrances more accessible and show that the park is open to everyone. A few rain gardens were created to better take care of rainwater, as well as a roof and sculptures interacting with the rain for aesthetic purposes. Additionally, existing plants and trees were cared for, and new ones were planted to create varied vegetation year-round. The area has been a park since 1860, therefore, efforts were made to preserve the historical space, such as using necessary amenities (benches, light sources) as well as improve the ecological function of the park. Special care was taken not to damage grown trees, such as the cherry trees, which blossom in the spring and are a popular attraction [Ref. 1, 2, 4, 5]