Okay, not an original answer at all, but my mother's funeral.

Ceremony is an important aspect of humanity. It's good to set aside some time to focus on what's important in our lives, once in a while. Whether it be pride in your country (like many of the moving moments in John McCain's funeral services) or life changing vows being made (weddings) or celebrating the birth of a child with the hopes we have for their successful journey into being happy well adjusted contributors to society (baby blessings) or any number of moving rituals when emotions are running high.

I've performed many ceremonies, with the hope of moving the participants to smiles, tears, pride, or any appropriate emotional feeling, to achieve the desired outcome... A feeling that something important is happening, or has happened, that the human spirit needs to recognize, to feel really human, and experience. It's important to honor those moments.

Many ceremonies have moved me, too many to mention, since my business is ceremonies, though it's the couple's words, or the family's sentiments that moved me to tears in ceremonies I've performed. But there were some ceremonies I've witnessed that simply did not move me or anyone in the room. It's because of those experiences I had and disliked that was the reason I chose to create ceremonies for a living.

Sometimes a human just has to cry... I joke to my clients that I'm not happy unless someone cries, and laughs, and smiles, of course.

Military funeral; a real punch in the gut. I hope I never have to attend another one of those.

When I took the obligation to become an active member of my union and I admitted my powerlessness and fucked-upedness in my EA meeting. Teared up and my voice broke both times.
Also giving my father's eulogy.

A US naturalization ceremony for a friend.

In 1999 when my mom passed away. We had a friendship gathering on the beach and then we took her ashes out to sea and relased her for her last dive. Prior to leaving the beach, all of a sudden there were butterflies everywhere. I know it was coincidental but man, was it wonderful for that split second to believe she was doing a fly by.

Watching my sister graduate medical school.
Me graduating college.

The one I performed my self !
I was in USA for about two weeks . Next door aprtmnt lady , mother of two young kids , I ll say 7 and 11 probably , a drunk , and a horrible mother if u ask me . My English was limited but my antennas were up and some things are international .. a parade of men in her place in the two - three weeks , and I was wondering w her young daughter just been there ... the men were also looking scetchy and shitty ..
I met the litle people and even if not speaking much English , the litle girl got attached . Taught her how to bake cookies . She taught me how to go to supermarket and find things ! I was amazed how her mother will let her come w me , even if just got my American driving licenses , and she knew nothing about me other than husband a junior marine officer and me from Italy / Greece ..
Litle girl had a rabbit and to keep it short ( too late !), rabbit died one day . The world collapsed of course . And I found my self bullshiting the litle girl and it was worth it ?
We got a scarf of mine ( an expensive one I MIGHT ADD !!) , a shoe box , flower petals , and we placed rabbit to his last home , until we see it again in heaven !( yeah , I know !)
The marine came home from the office and dig a litle hole at back of bulging (!) and I said some touching fair well dear rabbit things ", and we all cried , and we had icecream afterwards .
I still wonder what happend to that " family ". Actually don't give a rats behind about mother , but the kids ?
We moved away few months later to our first house . I do not attend any ceremonies . I refused to go to my fathers cremation , he won't like it anyways , a firm atheist , he couldn't care less and neither and I ?

I’ve been thinking about this for a few hours and I just can’t come up with anything. Surly, at some point, there was an instance, but it eludes me.

i've been moved by many moments but if any of them happened to be ceremonial, i can't recall. i've enjoyed witnessing some ceremonies, chief among them the inauguration of president jimmy carter (not on tv but in person -- i was there) and his subsequent swearing in of attorney general griffin bell (i worked for doj at the time, and we got to go down to the rotunda and watch that ceremony). but moved? every time i was sent on business from the warehouse-like sixth floor of the doj down to the carpeted (even the hallways) fifth floor (where the attorney general's offices were), i would stop for a minute in front of one of the portraits that lined the hallway walls. most of the portraits were what you would expect: full-on formal pictures of the gentlemen in question staring back at you, doing their best to look serious and competent. the one that caught my attention and held it every time was different. it was a profile of bobby kennedy walking, windblown, along a beach, wearing his late brother's jacket. i stopped and gazed and was moved.

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A funeral for an 8-year-old child who died in apparently perfect health. It nearly killed me, being there with her parents, trying to be helpful and knowing there wasn't a damned thing I could do.

Can't remember ever beign moved by one....

I have performed over 3000 weddings and around 250 funerals.
I tend to get choked up a little with some of them based on circumstances but have always maintained composure.

I don't think I cried at either of my weddings....

That said....I've been through about a dozen where I was being honored in some capacity -- graduations and career oriented ceremonies-- those were probably the most meaningful to me personally.

I've been to the opening ceremonies for four Olympic Games and one closing ceremony....those were amazing.
I've been to a handful of retirement ceremonies of friends...those were standard issue.....as well as hundreds of weddings and funerals for friends.

I don't there is just one out of all of these that was the ultimate ceremony for me.

My son's Eagle Scout Presentation.

The unknown soldier service.Oh yes and the impeachment of trumper.

Rembrance Day ceremonies usually get me. Especially if there's native drums and singers.