Four years after the Sept. 11 terror attacks on the United States, the nation continues to heal as the world combats an ever-present global threat.

Funerals for victims are still being held, Hollywood has confronted a subject it once avoided and the government continues to refine its approach to the War on Terror (search).

Remembrance ceremonies this weekend are being held around the country, and plans for memorials are being developed, reworked and criticized.

FOXNews.com takes a look at where things stand four years after 19 terrorists hijacked four airplanes and caused the deaths of nearly 3,000 people.

Planning the Memorials

A Sept. 11 memorial design was chosen to honor the 40 people who died on Flight 93 (search), which crashed into a Shanksville, Pa., field after passengers fought terrorists for control of the plane. The winning memorial consists of a chapel with 40 chimes, one for each of the passengers and crew who died. Pedestrian trails and a roadway run through the park leading to a visitor center and the actual crash site. The memorial will span 2,000 acres.

In Washington, D.C., a Freedom Walk was planned for Sunday beginning at 10 a.m. at the Pentagon's south parking lot.

The Defense Department plans to open the site of the planned Pentagon Memorial (search) and the existing America's Heroes Memorial (search) to the public on Saturday, from 10 a.m. to 2 p.m. The outdoor memorial, which is in development, will feature 184 illuminated benches, arranged according to the victims' ages, from 3 to 71, a Department of Defense press release said.

The America's Heroes Memorial is inside the Pentagon, near where American Airlines Flight 77 crashed. Included in this memorial are black acrylic panels engraved with the names of those killed, as well as a book filled with photographs and biographies.

In New York, construction on a memorial is expected to start next year for completion in 2009, according to the Lower Manhattan Development Corp., the organization in charge of coordinating the rebuilding of Lower Manhattan.

A cultural center at the World Trade Center site likely will include a visual arts area, a visitors' section and a center focusing on the global struggle for freedom, according to plans announced in May. It is designed to be suspended from a support bridge and its crystalline surface will be sprinkled with glass prisms. The building's roof will be landscaped.

But some friends and family members of victims say the center would distract from the tragedy it's meant to commemorate and that it would dishonor the memory of their loved ones.

Already set up is a public viewing wall around the site's perimeter, which lists the names of the dead and includes the history of the site, according the LMDC Web site.

Rebuilding Lower Manhattan

A design for a replacement building to the Twin Towers was announced by New York Gov. George Pataki earlier this year, but the initial plan was revamped to address safety concerns broached by the police department.

If built, the 1,776-foot Freedom Tower would be the highest building in the world.

In other developments, officials in early September broke ground on the World Trade Center transportation hub.

"Today we begin to take back a site to restore something that was taken away from us on Sept. 11," said Anthony Coscia, chairman of the Port Authority of New York and New Jersey, which owns the site and commissioned the project.

The station is set to open in late 2009 and will also link the commuter rail lines under the Hudson River to city subway lines.

Officials marked the ceremonial kickoff of construction on the transit hub by releasing two white doves.

In another sign that New York City was getting back on its feet, one of China's largest real estate companies was seeking to acquire space in the city — possibly in the reopened 7 World Trade Center, which collapsed after the Twin Towers were struck, the New York Post recently reported.

Healing Continues

In the days following Sept. 11, 2001, the search-and-rescue mission shifted into a recovery effort, as volunteers worked day and night, sorting through debris while stubborn fires burned for weeks.

Hundreds of funerals were held as American flags began appearing on homes, cars, highway overpasses and buildings in a sign of unity, and just days before the fourth anniversary of those events, the funerals continue.

Firefighter Gerard Baptiste's remains were not identified until earlier this year. With the echo of bagpipes and firefighters in dress uniform, the services for him at St. Patrick's Roman Catholic Cathedral were eerily reminiscent of countless others in the months after the Sept. 11 attacks.

Baptiste's death spurred his fellow firefighters at Ladder 9 to finish a project their lost colleague had started: the restoration of a rusted-out 1979 Honda CB750 motorcycle. A documentary, "F.D.N.Y. Dream Bike," recounted the rehabilitation effort.

Various support groups have been established to help survivors, family and friends through the healing process, but some take a different approach to getting over the loss of a loved one.

Patrick Dowdell, who lost his father four years ago in the World Trade Center attacks, wears a steel bracelet stamped with "Lt. Kevin Dowdell 9-11-01" with his West Point cadet grays. Pictures of his father in his firefighter uniform are taped to the wall in his quarters, and he still tries to live by his father's standards.

"I think about him," Dowdell said. "If he was here right now, what would he think about this or about that? I think he'd be pretty excited about what's happening."

Dowdell is now a senior at West Point, set to graduate in May. His class was the first to enter the U.S. Military Academy after the Sept. 11 attacks, but the looming reality of Army life is particularly poignant for this 22-year-old from New York City. The son who lost his father to terror is poised to join the fight against it.

"I'm going to go into the infantry," he said, "and I want to kill terrorists."

Dowdell believes his father was in the South Tower when it fell, though he'll never know for sure. All that was found of the 46-year-old was his pry bar etched with his initials. It's kept at the family's home.

His plan for Sept. 11, 2005, was clear: to walk across the Brooklyn Bridge to Ground Zero with his mother.

Hollywood Tackles Touchy Subject

After years of silence on the issue, Hollywood has begun to feature the attacks as the storyline for movies, miniseries and documentaries.

Click here to read a story by FOX News' Catherine Donaldson-Evans on Hollywood's approach to Sept. 11, 2001.

Two films — one from Paramount Pictures, the other from Universal Studios — and a miniseries on ABC are due out in 2006, when it will have been five years since the tragedy that set the country and the world on a different path, and others have been planned or recently aired.

"It really was just a matter of time before they decided to take this on," said Missy Schwartz, a correspondent for Entertainment Weekly who wrote about the forthcoming Sept. 11 projects. "Hollywood is always looking for dramatic stories."

While some disagree with the portrayal of Sept. 11 on the big screen, saying it reopens painful wounds, others believe the tragedy must not be forgotten and video footage is a good way to remember.

Terror Attacks, Arrests Ongoing

Despite the positive steps taken in the aftermath of the attacks, worldwide terrorism continues with U.S. allies in the War on Terror being targeted.

Two prime examples include the summer transit bombings in London, in which more than 50 people lost their lives in a span of minutes, as well as the nearly simultaneous Madrid train bombings, which killed 191 people on March 11, 2004, during the peak of the morning rush hour.

Al Qaeda, the terrorism group led by Usama bin Laden, has claimed responsibility for the London attacks, which also occurred during the height of the morning rush.

The Madrid blasts were claimed by militants who said they had acted on Al Qaeda's behalf over the presence of Spanish troops in U.S.-occupied Iraq.

Worldwide law enforcement efforts have identified and broken up terror "sleeper" cells, as well as arrested and prosecuted many suspects.

In one recent example, a German court convicted a Moroccan man suspected of assisting the Sept. 11 hijackers of membership in a terrorist organization.

Mounir el Motassadeq was convicted in August after a yearlong trial and sentenced to seven years in prison.

Stepped-Up Security

Law enforcement authorities have urged civilians to report any suspicious activity they witness, and terror tip hotlines have been set up post-Sept. 11.

In New York City, for example, transit riders are urged to report suspicious activity, with Metropolitan Transportation Authority posters reminding: "If you see something, say something." Train and subway riders are subject to random bag searches.

Nationwide security efforts include the establishment of the Department of Homeland Security, whose Ready America Web site provides tips for civilians on how to be prepared in the event of a terrorist attack, as well as a color-coded terror alert system for identifying the threat risk. The nation is at yellow, meaning there is an elevated risk for a terror attack.

Air travel initiatives include undercover law enforcement agents on flights, as well as tightened passenger screening. Butane lighters recently were banned from air travel, and passengers may be asked to remove their shoes for inspection by airport screeners.

Click here to view a comprehensive list of items banned from flight.

Travelers are advised to show up two hours before their flight.

In addition, travelers' names are screened to see if they show up on terror lists, which include those individuals identified by the government to be affiliated with terrorism.

Security surcharges have been added to the cost of airfare, and President Bush has proposed air safety measures to combat terror risks. Some of the initiatives include mandating Federal Aviation Administration workers take charge of screening responsibilities.

Government Criticized for Disaster Handling

The response to Hurricane Katrina showed flaws in a system many thought was in good shape following Sept. 11, 2001. The organization in charge of the relief efforts, the Federal Emergency Management Agency, has been criticized for its slow response in getting aid to victims and providing transportation out of New Orleans immediately following the storm.

Emergency workers are still recovering bodies and thousands were estimated dead. Many died of dehydration and other ailments in blistering heat and other adverse conditions as they waited for days for transportation and shelter.

As the enormity of the Gulf Coast damage gradually came into clearer focus, FEMA Director Michael Brown came under fire for a number of comments seen as insensitive or ill-advised.

For example, he acknowledged he didn't know there were some 20,000 evacuees enduring heinous conditions at the New Orleans convention center until a day after their difficulties had been widely reported in the news.

Brown, for his part, is trying to shrug off the criticism.

"People want to lash out at me, lash out at FEMA," he told reporters. "I think that's fine. Just lash out, because my job is to continue to save lives."

Several lawmakers on Capitol Hill have introduced bills to investigate the handling of Hurricane Katrina and to restore independence to FEMA, in light of other natural disasters or terror attacks.

Sens. Barbara Mikulski, D-Md., and Hillary Rodham Clinton, D-N.Y., introduced legislation calling for removing FEMA, the chief agency in the federal government's response to disasters since 1979, from the Department of Homeland Security, where it was moved under the current Bush administration. The bill would return its status as a Cabinet-level, independent federal agency.

Under the senators' bill, the FEMA director would report directly to the president and be in charge of coordinating other federal agencies in relief and rescue efforts for any national disaster. In March 2003, under the Homeland Security Act of 2002, FEMA was relegated to a subagency of DHS reporting to that department's secretary.

Their second measure creates an investigatory commission to probe the handling of relief efforts. The Katrina Commission will be modeled after the one established after the terrorist attacks of Sept. 11, 2001.

The Sept. 11 commission has recently come under fire, with one congressman alleging it withheld information from what it reported to the public on its findings.

Rep. Curt Weldon, R-Pa., a champion of integrated intelligence-sharing among U.S. agencies, said Sept. 11 panel members claimed they had not been given critical information on "Able Danger," a military intelligence unit that had identified terrorist Mohamed Atta and other hijackers a year before the attacks.

"The commission's refusal to investigate Able Danger after being notified of its existence, and its recent efforts to feign ignorance of the project while blaming others for supposedly withholding information on it, brings shame on the commissioners, and is evocative of the worst tendencies in the federal government that the commission worked to expose," Weldon wrote in an August letter to the former chairman and vice-chairman of the commission, formally known as the National Commission on Terrorist Attacks Upon the United States.

Those affected by tragedy may contact the Red Cross via its Web site, which lists contact information for support groups across the United States.

FOX News' Catherine Donaldson-Evans and The Associated Press contributed to this report.