The memorial honoring World Trade Center victims will include a forest of oak trees with a clearing for September 11 gatherings and a Memorial Hall between the twin reflecting pools that will mark the footprints of the lost towers, officials announced yesterday.

Among the new elements of the site released yesterday were the Memorial Hall, a 1.5-acre clearing at ground level for public gatherings, and the exposed stumps of columns that supported the twin towers.

John Whitehead, chairman of the Lower Manhattan Development Corp., the agency overseeing rebuilding, called Memorial Hall a new public space where visitors will be able to “review a directory of the names, locating their loved ones among the souls that are there.”

Governor Pataki, Mayor Bloomberg, victims’ family members and designers also attended a news conference a few blocks from the site to release details of the memorial design.

“We have to have a memorial that really allows us to connect the sheer enormity of the twin towers to the individuals that were taken from us,” Mr. Bloomberg said, “and I guess to the higher powers in whose hands we really place our fragile lives every day.”