Remembering 9/11: Hours for September 11 Memorial and Museum, Flight 93 Memorial in Shanksville, PA

On Wednesday, people nationwide will commemorate the 18th anniversary of the September 11, 2001, terrorist attacks. Following the attacks at the World Trade Center, Pentagon and on United Airlines Flight 93, several memorials were erected across the country.

The National September 11 Memorial and Museum, located in New York City, is the country's principal institution for learning about the events of that day, the implications and the aftermath. With 110,000 square feet of exhibition space, the museum uses multimedia displays, archives, narratives and monumental and authentic artifacts to tell the story.

Those who find themselves in New York City on September 11 will not be able to visit the national museum, although there will be time to see the memorial.

Usually, the museum is open from 9 a.m. ET until 8 p.m. ET on Sunday through Thursday and then until 9 p.m. on Friday and Saturday. However, on Wednesday, in observance of the 18th anniversary, the museum will be closed to the public for the entire day.

The Historical Exhibition, one of two main exhibits, is designed to teach about the events of the day as they unfolded, the historical context leading up to 9/11 and life after the attacks. In the Memorial Exhibition, visitors can see photographs of the victims and learn about their lives by using touch-screen tablets to look up individual profiles. There is also a rotating selection of victims' personal items on display. The items were donated to the museum by family members.

Witness at Ground Zero, another exhibition available, draws on the more than 500 pictures that were captured by French photographer and video director Stephane Sednaoui. After witnessing the attacks, he volunteered in the rescue efforts at Ground Zero.

9/11 memorial museum flight 93 hours
A flag amongst the names of the those who died at the National September 11 Memorial in New York City. On the 18th anniversary of the attacks, the museum will be closed to the public and the memorial will be closed until 3:00 p.m. ET. Tim Clayton/Corbis/Getty

The memorial, which is free of charge and usually open daily 7:30 a.m. ET until 9 p.m. ET, will be closed for a large portion of the day. At 3 p.m. ET, it will reopen to the public.

The memorial occupies eight acres at the World Trade Center and serves as a tribute to the past, as well as, a place of hope for the future. Along with inscriptions of the names of all 2,977 people killed in the various attacks in 2001, it also has the names of the six people who were killed during the 1993 World Trade Center bombing.

Twin reflecting pools were placed where the Twin Towers once stood and features the largest manmade waterfalls in North America.

After the passengers on United Airlines Flight 93 realized their plane was hijacked, they bounded together, formed a plan and fought back. Their act of bravery was enough to prevent the deaths of others, but unfortunately, resulted in the loss of the passengers' lives.

Remembered for their heroism in the face of terror, the passengers are memorialized in Shanksville, Pennsylvania, where the plane crashed. The Tower of Voices, a collection of 40 wind chimes, representing the 40 passengers and crew members, stands at 93 feet tall.

Free to visit, the memorial site will host the Eighteenth Anniversary Observance on Wednesday beginning at 9:45 a.m. ET. The memorial will open at 7 a.m.