News: new images unveiled this week reveal that the third and final phase of New York's High Line park will feature an enclosed amphitheatre filled with plants.

The bowl-shaped structure will create a new north-east gateway to the popular park - created across an abandoned elevated railway by architects Diller Scofidio + Renfro, landscape architects James Corner Field Operations and planting designer Piet Oudolf - and will form part of a new stretch wrapping around New York's old freight train yards.

Named The Spur, the structure will be positioned at the widest point of the High Line, across the intersection of 10th Avenue and West 30th Street, and is conceived as "an immersive experience of nature".

Tiered seating will line the perimeter of the bowl, surrounded by woodland grasses, ferns and perennials. Snakebark maple and black tupelo trees will be planted around the edges, while sliced openings will offer views out towards the Hudson River. Public toilets will also be included.

"The challenge was, there was so much expectation on this spot, we knew it had to be something extraordinary," said Friends of the High Line co-founder Robert Hammond, speaking to New York Daily News.

"On the High Line, you're always aware of the city around you," he added. "We wanted to create a space where people could be immersed in nature."

High Line at the Rail Yards is set to open in late 2014, with The Spur due to follow on within two years. It will link up with the two existing sections, which opened in 2009 and 2011. See more images of phase one and phase two in our earlier stories.

The latest section is currently overgrown with wildflowers and grasses that grew up when the trains stopped running the 1980s, but is set to be upgraded with walkways, balconies, benches that peel up the ground and a children's play area.