Interlaken Park is located in the North Capitol Hill neighborhood at 2451 Delmar Dr E, 98102. It is 51.7 acres.
Interlaken Boulevard was partially laid out along the lines of an early bicycle path as part of implementing the 1903 Olmsted plan. The boulevard runs a shady 3 miles westward from Lake Washington Boulevard and across the north-facing wooded slopes of Capitol Hill. A branch of the parkway travels up the slope to access the top of Capitol Hill19th Ave. E and E. Galer.
In the 1903 Olmsted Bros. report, the ‘Volunteer Hill Parkway’ is described as ‘one of the most desirable’ branch parkways that would connect Washington Park with Volunteer Park. Bicycle trails already existed in that area as part of the 25-mile bike trail system developed by Assistant City Engineer George Cotterill in the 1890’s, and the roads were planned to follow some of these original paths, traversing the north slope and ascending along the north crest of Volunteer Hill (Capitol Hill). The report recommends acquiring enough park property to include the best portions of the wooded ravines and enough of the bluffs to control views east to Lake Washington and the Cascade Mountains. The report also recommended acquiring extra land, especially to the bottom of the steep slopes, to discourage any attempt at development; this would not only provide some protection from landslides but also prevent excessive grading that any private building would require.
The eastern half of the boulevard from Washington Park to 21st Avenue E is a traditional boulevard, a roadway meandering through a residential neighborhood with a wide right-of-way that allows curves in the road and large planting areas. The western half of the boulevard continues as a road through Interlaken Park but is set within a larger, steeply wooded setting. The Olmsted Bros. recommended a gently curving road that generally follows the contours of the slope and suggested several rustic bridges over steep ravines, in part to help soften the otherwise tight curves. The plan also added pedestrian paths that access some of the steeper terrain.
By 1908, plans to extend the “Volunteer Hill Parkway” southward up the hill and paralleling 10th Ave were apparently abandoned, and Olmsted instead provided conceptual drawings for a large concourse and view platform to serve as the western terminus for Interlaken Boulevard. This concourse was proposed where Bagley Viewpoint now exists. The 1909 Commissioner report describes this boulevard as the “entrance to the [boulevard] system from the down town section of the city” and reports Interlaken Boulevard as being so developed that it need not be discussed. They do, however, describe the section of boulevard west of 19th Avenue as being under construction. The 4100 ft long roadway extended the roadway portion of the boulevard from 19th Avenue and E Galer St. west to Roanoke St and Eleventh Ave N.
An addendum to the Park Commissioners report is a letter from the Olmsted Bros. firm (dated Jan. 5, 1908) that speaks specifically to that extension. A major connection of the Boulevard to the west lay along one of the existing bike trails, but this trail crossed a property owned by Adelphi College (now the campus of Seattle Prep). The firm evaluated whether the boulevard would inhibit the college from any expansion plans. They determined that several new buildings situated around a central green space could all be built on the plateau at the top of the bluff. The Olmsted Bros. determined that the boulevard was planned to be installed on a slope that was too steep to be used for any large institutional building and that the owners of the property would not be adversely affected by the construction.
In 1913, several acres were set aside from Interlaken Park and re-named to honor Louisa Boren Denny, a Seattle pioneer. This property encompasses the scenic view point at the top of the bluff at the original pedestrian connection from Interlaken Park to Volunteer Park.