Here we are, 17 years to the day after commercial airliners hijacked by Middle East terrorists brought down the twin towers of the World Trade Center in New York, caused serious damage at the Pentagon and apparently had as a target the Capitol, White House or some other important place in Washington, D.C.

The death toll of innocent Americans that day was horrific — nearly 3,000 — and many first responders and others who were in close proximity to the planes’ impacts continue to suffer adverse health consequences from their contact with debris and the poisoned, foul air that they had no choice but to inhale.

Unfortunately, this part of Pennsylvania became an unwanted — nevertheless heroic — chapter in the 9/11 tragedy as the fourth airliner, Flight 93, on a flight path heading toward Washington, crashed in a field near the small Somerset County community of Shanksville.

It crashed as brave passengers tried to wrest control of it from the terrorists aboard.

Thousands of families were shattered that day, with no part of this great nation spared. Even some families that did not experience a loss of life still have not recovered completely from the pain and horror that they witnessed either in person or by way of news accounts on that terrible day and during the days afterward.

Seventeen years later, despite the invisible “walls” erected by the nation’s intelligence agencies and military to try to prevent another day like Sept. 11, 2001, there can be no absolute assurance that America will never again be so badly victimized.

Americans must be on guard unceasingly against terrorism’s tentacles.

Amid that uninterrupted vigilance today, however, is the necessity to remember and offer prayers, not only for all of the 9/11 victims living and deceased, but also for the nation as a whole.

That’s why memorial services and programs of remembrance are being held today at all of the terror sites and in many churches.

The Shanksville-area crash site, now part of the Flight 93 National Memorial, will have as participants in its ceremony President Donald Trump and first lady Melania Trump. It will be the president’s closest trip to Blair County since he appeared in Johnstown for a rally during the 2016 presidential election campaign.

But this day of remembrance at the Shanksville site will have special significance for Blair and its residents. Today’s ceremony will officially introduce to thousands of people the memorial’s 93-foot Tower of Voices, which was constructed by L.S. Fiore Inc. of Altoona.

Located near the national memorial’s entrance, the tower has 40 wind chimes representing the crew and passengers of the ill-fated flight. The tower was described in a Mirror article of Sept. 9, 2017, as a “monumental musical instrument” that will produce music that is ever-changing.

Besides Fiore’s connection to the Flight 93 site is that of Pennstress, which fabricated in Roaring Spring the precast concrete components for the tower.

With the Tower of Voices in place, the national memorial is prepared fully to tell and retell the 9/11 story.

That story cannot be told too many times, and President and Mrs. Trump will have many opportunities to encourage others to visit the memorial for a touching experience that they’ll always hold close to their heart.