Timeline: In Terror's Wake

Terrorists hijack four jetliners and crash them into the World Trade Center, the Pentagon and a Pennsylvania field. The twin towers and 7 World Trade Center collapse.

Osama bin Laden identified as prime suspect in the attack.

Nineteen hijackers identified and linked directly to bin Laden.

Wall Street trading resumes, ending stock market's longest shutdown since the Great Depression. Dow loses 684.81 points, its worst-ever one-day point drop.

First air strikes launched in Afghanistan. Bin Laden, in videotaped message, praises God for Sept. 11 attacks.

President Bush signs anti-terrorism bill giving police unprecedented ability to search, seize, detain and eavesdrop in pursuit of possible terrorists.

First wave of Marines lands near Taliban stronghold of Kandahar.

Hamid Karzai and his transitional government sworn in to lead Afghanistan.

President Bush signs legislation creating Department of Homeland Security.

President Bush signs bill establishing independent commission to investigate the Sept. 11 attacks.

Congressional inquiry issues final report on intelligence failures leading up to terrorist attacks. Key recommendations include creating Cabinet-level director of national intelligence.

Thousands of newly hired government workers begin screening every checked bag at the nation's commercial airports for explosives.

Moroccan student Mounir el Motassadeq receives maximum 15-year sentence in Germany for helping Sept. 11 hijackers. It was the first conviction tied to the terror plot and was later overturned.

Motassadeq was subsequently convicted of belonging to a terrorist organization and sentenced to seven years. He was acquitted of more than 3,000 counts of being accessory to murder. He is released from prison in February 2006 when a German federal court rules he shouldn't be jailed with appeals pending.

Architect Daniel Libeskind's Freedom Tower plan, including a 1,776-foot spire and sunken memorial, chosen for rebuilding trade center.

Design announced for Pentagon memorial, with 184 benches - each placed over an individual reflecting pool - inscribed with a victim's name.

The 9/11 Commission holds first public hearings, a half mile from ground zero.

The Port Authority releases 2,000 pages of transcripts from emergency calls and radio transmissions following attacks.

Firehouse across from World Trade Center re-opens.

The New York City Medical Examiner places final death toll from trade center attacks at 2,749.

9/11 Commission concludes 20 months of investigation with a preliminary report that fails to find "credible evidence" of collaboration between Iraq and al Qaeda on attacks.

9/11 Commission delivers final report to President Bush; its key findings include the failure of the Bush and Clinton administrations to make anti-terrorism a top priority.

President Bush signs Intelligence Reform Act, a historic overhaul of the national intelligence system.

Zacarias Moussaoui, the only person indicted in the U.S. for the attacks, pleads guilty to conspiring with the Sept. 11 hijackers. He is sentenced to six life terms to run as two consecutive life sentences in May 2006.

A design is chosen for the Flight 93 National Memorial in Pennsylvania. The design pays tribute to the heroic struggle by passengers who thwarted an attack on the nation's capital.

Syrian-born businessman Imad Yarkas was sentenced to 27 years in prison for leading an al Qaeda cell and conspiring to commit murder in the Sept. 11 attacks. Yarkas conviction was overturned on appeal in April 2006, though a separate conviction of leading a terrorist cell was upheld, and Yarkas was sentenced to 12 years in prison.

A second man, Ghasoub al-Abrash Ghalyoun, was acquitted of all charges of collaborating with a terrorist group.

Construction workers near the World Trade Center site discover more bone fragments and human remains. In September, hundreds more fragments are found on the roof of the former Deutsche Bank building.

The Pentagon releases the first video images of American Airlines Flight 77 crashing into the military headquarters.

Opening of 7 World Trade Center, the third building to fall on Sept. 11 and the first to be rebuilt.

Final design for the Freedom Tower to be built at ground zero is formally unveiled. The tower will be the centerpiece of the rebuilding of the World Trade Center in downtown Manhattan. It is estimated the tower will be completed in 2012 or 2013.

A new study by Mount Sinai Medical Center reports that almost 70 percent of rescue workers who were at Ground Zero have developed symptoms of respiratory illness. This feeds long-standing criticism that not enough has been done to address these workers' health issues.

The fifth anniversary of the terrorist attacks are marked at the World Trade Center site, at the Pentagon, and around the world.

The first steel columns are installed in the Freedom Tower's foundation.

A fire in the abandoned Deutsche Bank office building at the edge of Ground Zero claims the lives of two firefighters, and revives criticism of the slow pace of rebuilding on the WTC site, and charges of improper handling of a building long considered to be one of the most contaminated in the U.S.

Pope Benedict XVI visited ground zero as part of his first pilgrimage to the U.S. as pope. Benedict prayed silently, lit a candle and offered words of prayer. Following the prayer, he blessed the ground in all four directions and then blessed those gathered. He also personally greeted some family members of those who died on Sept. 11, survivors, and first responders.

Construction workers installed the first steel column for the Sept. 11 memorial at ground zero. The 7,700-pound column was erected by the footprint of the World Trade Center's north tower. The "Reflecting Absence" memorial will set two giant pools over the twin towers' footprints.