New York City's High Line is a public park built on an abandoned elevated railway that nature reclaimed over decades.

The High Line was originally part of the West Side Improvement Project, which opened in 1934 to remove dangerous trains from Manhattan's streets. By the 1960s, the rise of interstate trucking led to a decline in rail traffic, and the final train delivered three carloads of frozen turkeys in 1980. For the next quarter-century, the structure underwent a biological process known as spontaneous succession, where pioneer species of plants colonized the harsh, gravel-covered environment without human intervention.In 1999, neighborhood residents Joshua David and Robert Hammond founded 'Friends of the High Line' to advocate for the structure's preservation as public space. They were inspired by the Promenade Plantée in Paris, which was the first elevated park in the world. The design team, led by James Corner Field Operations and Diller Scofidio + Renfro, intentionally incorporated the wild, self-seeded landscape into the final park architecture. This 'agri-tecture' strategy blends hard paving with soft planting beds to mimic the way the tracks looked during their period of abandonment.The park now spans 1.45 miles and features over 500 species of plants and trees, many of which are native to the New York region. This diverse ecosystem provides a critical corridor for pollinators like bees and migratory birds in a dense urban environment. Research from the University of Pennsylvania suggests that such green infrastructure projects can significantly reduce the 'urban heat island' effect by lowering surface temperatures. Today, the High Line attracts nearly 8 million visitors annually and has sparked a global trend in repurposing industrial infrastructure for community use.