HOW do you design a shed for a unicorn? How do you build a frame for the Statue of Liberty? Or, put a bit more precisely, how do you design an environmental education center for Jersey City on top of a former trash heap?
If the first two questions sound perplexing and the last almost comic, they were the challenges handed to architect Michael Graves in an assignment by New Jersey's Department of Environmental Protection.
The designer - perhaps best known for his controversial but award-winning post-modernist civic center in Portland, Ore. - had a difficult mission. He was to create an interpretive center for Liberty State Park on what may be the most spectacular open space in urban America - a 750-acre site overlooking Ellis and Liberty Islands, the World Trade Center, New York Harbor, and Manhattan - shaping a built environment appropriate to the natural one.
The tract of land has acquired allies since the day in 1968 when its executive director, Jerry McCabe of the Department of Environmental Protection, came upon this ''abandoned railroad land covered with debris.'' Its stunning site, surrounded by water (the Hudson, the Morris Canal Basin, and Black Tom Channel), has further development scheduled for it. Its administration is awaiting money to fund a Liberty Park Development Corporation.
The structure (now nearing completion of its exhibits and programs before opening) was designed to meet some specific needs - for exhibition galleries, offices, and an auditorium. Still unclear, however, is the function of the building.What began with instructions to create an ''interpretive wildlife center'' evolved into a building to interpret the park itself. What the architects built as a ''way station'' for environmental education, the staff now calls a ''lookout.''
Nor is the project complete. Plans for a golf course and reconstruction of an 1867 railroad terminal are still in the works - part of the so-called ''action program'' (the master plan for further development updated by landscape architects Wallace, Roberts & Todd, of Philadelphia and galvanized by director McCabe) now awaiting implementation and funding from the New Jersey Legislature.
SOME architects might have tried an ecological matchup. To parallel the marshlands, their materials might have been woodsy, their siting inconspicuous, their interior open and inviting, bringing in the weedy outdoors through picture-window wraparounds.
With others, there might have been a maritime theme, a nautical motif with steamship rails and portholes, flags flying, and metaphorical sails projecting a sense of the sea.
Graves, however, took what can only be called a Gravesian approach. Applying what he describes as ''figurative architecture'' to the task, he has come up with a bold statement drawn from his repertoire of classical references, pointed roofs, and heavy columns.
There is a monumental, tomblike feeling to the blocky columns topped by a helmet of lattice. Overall, one is struck by a post-modernist mix of periods - from 1930s colors and window proportions to Mediterranean massing of cubed forms , from 1890s gray wood-shingle surfaces to high-tech roofing - and ranging in style from frontier fortress to Hollywood stage set. Though modest in size, the center manages to hold its own with, or perhaps against, the landmarks of the World Trade Center and the Statue of Liberty.
Inside, the forms have equal substance. Recessed bays, simplified hearths, raised ceilings, and the chunky simplifications of the columns - all painted in the pale mauve, yellow, and green palette that the architect has made his vocabulary - give character to a space that might have been as bland as ''government green.''
Despite the low budget ($1.2 million for 6,300 square feet plus breezeway, open air pavilion, and way station), the center has a real personality.
At once playful and ponderous, Graves's building displays the boldness of a monument without its forbidding qualities. By its columnar definitions, its heavy marking of entries, its architectural exclamation points of red cylinders along the roofline, the building is, in short, a compelling if mannered place - a shed, perhaps, for a unicorn.
And that is what gives the center its somewhat eerie aspect.
THE notion of using the center to tell some million visitors a year from the densest corner of the United States about the park, the past, and the urban and natural life of the region makes eminent sense. But the fact that the building's form so clearly preceded its definition of function may account for the weirdness of this striking architectural configuration.
In some ways, the center looks like an abandoned building from another era, a prop in a lifeless town. There is a strange sensation here, a time warp. The interior is so richly reminiscent of the 1930s, with its sculpturavP enings and shadows, its evocative hues and hearths, that it almost haunts the visitor. Chilly and empty, awaiting new tenants, the almost year-old structure has an air of belonging to the past, the present, and the future all at once.
For all its amazing potential, the park itself also has a strange presence on a late-fall day. Though it offers relief for both the nearby dwellers of Jersey City and an estimated 12 million residents within reach, the place is a kind of terra incognita.
Just off the New Jersey Turnpike, one drives past a wasteland of industrial buildings and pauses as railroad cars labeled ''liquids inflammable'' glide by. On one side is a grim ripple-sided structure, on the other benches resolutely looking to the wonderful waterside views. Yellow and blue flags line the processional road to the park. Sea gulls sit in the asphalt lots now empty in the off-season. This leads to a stunning sight of one of America's most profound symbols, the Statue of Liberty. If any single place in America represents the ironies of our industrial litter and the potential elegance of a waterbound coast, this is it.
And the center somehow takes on all this aura, too.
CAN Liberty State Park emerge from ''a disaster area, cluttered with every kind of trash, garbage, and debris'' along a waterfront consisting of ''dilapidated piers, sagging bulkheads and derelict vessels'' (as the report on its future describes it) to a place of pleasure or even grandeur?
The center, a major statement by the nation's most visible vanguard architect , bears the weight of that uncertainty. Graves's building is at once an architectural landmark and an architectural apparition. Its ghostly air demonstrates as strongly as any recent building how even the most forceful or sculptural designs can be obscured and overshadowed by elements far removed from the studios that practice its fine art.
Jane Holtz Kay writes architecture criticism for The Christian Science Monitor.