A lilac walk is a type of display garden that shows off lilacs in a dramatic fashion, along a path. It may have many flowering plants that maintain the interest of passersby, but is used primarily to display a collection of lilacs in an arboretum, botanical garden, or park.
Father John Fiala wrote that long ago Lilac walks were created that had a collection closely planted along a winding path that were very beautiful when the lilacs bloomed but were not very interesting when they weren't flowering. He suggested that the lilacs should be inter-planted with trees and shrubs that had a succession of blooms and fruit at other times of the year and that different species of Lilac that flowered later could be used to extend the lilac season (Fiala, 117).
Such a walk whether winding so that new views of massed lilacs open as you work your way around the latest turn or long straight paths that reveal distant vistas of lilacs planted in masses can attract all year long as well as providing examples of good (and bad) companions for these plants in your own home garden.
Arnold Arboretum in Boston, MA has a Lilac Walk of many varieties planted along a road.
Highland Park, Rochester NY has a fine example of an older style Lilac Walk.
Rutgers University has the Alice Harding Lilac Walk.