Parks in major metropolitan regions will have a new and expanded role in the health of urban life in the 21st century, potentially much more integrated, compared to the model of park as place where the city is not. Three leading landscape architects -- James Corner, George Hargreaves, and Michael Van Valkenburgh -- explored prospects and challenges in park-making at an event earlier this month at the Museum of Modern Art in New York hosted by the Forum for Urban Design and the Lincoln Institute of Land Policy. Corner said the 21st century park will be "big, productive, and new' -- at a larger, regional scale, citing Lake Ontario Park in Toronto; performing new functions in sustainability such as Fresh Kills Park and Shelby Farms Park in Memphis, Tennessee; and uniquely fresh, as in the case of the High Line, the abandoned elevated freight line in New York's meatpacking district that will open this summer as a kind of urban ecological trail. Hargreaves explored the need to rejuvenate distressed sites in central locations and engage in public-private partnerships, and cited major events like the Olympic games and London 2012 park as important drivers. There is both a universal quality of parks and a dynamic dimension relating to ecology, said Van Valkenburgh, who sees landscape as an agent of urbanism, as well as a clear economic benefit. As a respondent, this correspondent noted the role of citizen engagement and stewardship, recalling the rebellion engineered by Jane Jacobs and others at Washington Square Park, and current debates about density along the edges of the Rose Kennedy Greenway in Boston, the signature public space over the Big Dig. The panel was moderated by Toronto-based architect and urban designer Ken Greenberg, who was cheered by the "comeback of the public realm" even in the age of the Internet and social networks. An excellent write-up of the proceedings can be found at The Dirt: Landscape Architecture, Sustainability, and Environmental News, the weblog of the American Society of Landscape Architects.