The two organizations responsible for designing a memorial and rebuilding on the site where the World Trade Center once stood, have unveiled their first proposals for what Lower Manhattan might look like in the future.

The six proposals all incorporate a central transit hub similar to Grand Central Station. They also include new office buildings, containing more than one million square meters of office space, and the restoration of street grids that existed before the twin towers were built. Most significantly, however, every proposed plan begins with, and is built around, a memorial. The suggested memorials: a plaza, a square, a triangle, a garden, a park, and a promenade range from 1.5 hectares to more than four hectares in size.

The Lower Manhattan Development Corporation is overseeing the project with the Port Authority, which owns the space. LMDC Chairman John Whitehead insists nothing about the plans is final. Instead, he said they are intended to spark public discussion.

"Each of the plans represents a package of proposed ideas. These ideas can be mixed and matched and reconstituted based on public input, and on our architectural consultants continuing work," Mr. Whitehead said.

The memorial will be the subject of an international design competition. The public can also participate in a series of open discussions to be hosted by the LMDC, beginning in late July. Additionally, the plans will be on view on the Internet at, where visitors can take computer tours of the proposals and submit comments and suggestions.

The Port Authority and the development group hope to narrow the number of proposals to three in September, and to release a final plan in December.