Thousands are expected today at the World Trade Center to mark the anniversary of 9/11. Relatives, survivors, rescuers, and others will remember one of the deadliest terror attacks the United States has ever seen.

It has been sixteen years since that fateful day. A day meant to remember those who have passed has also become a day of strength. Customs have been made: ringing bells, moments of silence, saying the names of the dead. Some have even put personal touches to their remembrances, sending messages of love, memory, and humor out into the universe.

“Thank you, New York, for continuing to honor the victims of 9/11 and the privilege of reading their names,” Judy Bram Murphy added last year. She lost her husband, Brian Joseph Murphy.

According to Time, “nearly 3,000 people died when hijacked planes slammed into the trade center, the Pentagon and a field near Shanksville, Pennsylvania, on Sept. 11, 2001, hurling America into a new consciousness of the threat of global terrorism.”

This year will mark President Donald Trump’s first 9/11 anniversary as president of the United States of America. A native New Yorker, he is scheduled to hold a moment of silence along with the thousands expected to assemble. He will be joined by First Lady Melania Trump.

Defense Secretary Jim Mattis and General Joseph Dunford, chairman of the joint Chiefs of Staff, held a private observance for the families of victims this morning at 9:11am. The president attended, listening to the name-reading of the departed.

There was also a public observance, wreath-laying, and remarks.

According to TIme, “Vice President Mike Pence and U.S. Secretary of the Interior Ryan Zinke are scheduled to deliver remarks at the Flight 93 National Memorial near Shanksville.”

One of the planes crashed on this field when passengers and crew grappled with the terrorists.

Construction workers broke ground in Shanksville yesterday, with a 93-foot (28 meters) tall Tower of Voices memorial planned for the space. 33 passengers and 7 crew members died in the crash.

Since 2011, politicians have not been allowed to read names or give remarks at any 9/11 ceremony. In keeping with this tradition, the ceremony “on the National Sept. 11 Memorial plaza strives to be apolitical.”

Last year, then-presidential nominee Hillary Clinton attended the ceremony in New York, but had to leave abruptly. It was later revealed she had been diagnosed with pneumonia just days before.

Buildings crushed or destroyed due to the attacks are slowly being rebuilt. The third of four office towers is set to open next year. A Greek Orthodox church is also set to open. The $250 million performing arts center and memorial walkway are still being designed.