Mark Wahlberg, Ben Stiller, other stars remember 9/11 on 16th anniversary

Everyone remembers where they were on the morning of Sept. 11, 2001. And 16 years later, celebrities are pledging to never forget the tragedy of that dark day. 

Some, including Ben Stiller, paid tribute to lives lost. 

Hugh Jackman tweeted a tribute to the New York Fire Department. 

Melissa Gorga noted how we must continue to remember 9/11 despite the countless other calamities occurring across the country. 

Melissa Joan Hart remembered how Americans showed true heroism that day. 

"I will never forget the feeling of vulnerability and helplessness as I watched the towers tumble onto the streets below," she wrote. "But I will also never forget that there were [brave] souls who rushed in ready to help recover and rebuild; some at the risk of losing everything themselves." 

Mark Wahlberg reminded everyone to "unite" on this day. 

Donnie Wahlberg also called for unity, asking followers to "remember the ways Americans came together as one." 

Chip Gaines simply wrote that we will "never forget."