People who want to visit the September 11 memorial in New York City when it opens in two months will be able to start reserving tickets over the internet from Sunday.
Visitors will be able to get timed passes to see the memorial, which opens to the public on September 12, following events for victims' families on the 2001 attack anniversary a day earlier.
Memorial and museum president Joe Daniels told The New York Times that he expected demand to be great.
The parts of the memorial plaza that will be open to visitors in September can comfortably hold only 1,500 people at a time.
There will be no limits on how long a visitor may spend on the plaza, once they pass through security.