My first born son coming into the world. I had worked as a nurse and i had seen all types of deliveries, but seeing my own flesh and blood being born was something else. Its an experience every father should have.

 The most memorable thing that i ever saw was my 4 year old son going to school for the first time

 The most memorable thing that i ever saw was my sons father walk out of our lives

 Well there are lots of personal things that are very memorable. But for me its 9/11 I remember watching it like it was yesterday, I remember exactly what I was doing and where I was when the second plane crashed. To a lesser extent the same is true of when I heard about Princess Diana, even though that was a great shock it didn't have the global implications of 9/11. I think the most memorable memories are the ones which we share with others.

 The most memorial thing i ever saw was the day my brother passed away from injuries in a car accident that is something i will never forget.

 Oh dear - I bet you wished you hadn't asked now. I'm pretty sure Jennifer88 was looking for positive uplifting answers here, guys, not what's the most depressing thing you can remember. Unfortunately it does seem to be the human condition that unpleasant memories, thoughts etc stay with you and make a deeper impression than the happy positive things, and most of the answers here seem to confirm that. Hope you don't get too miserable reading these responses, Jennifer88! ;o)

 The most memorable thing I ever saw was Regan Mcniel's possessed face on the exorcist.

 I have to agree with JohnLock. Seeing the tragic events happening on tv on 9/11 was something I will never forget. I can't begine to imagine what it must have been like living there and seeing these events happening right before your eyes!

 I have to admit that 9/11 is something I'll never forget. But I can say, and I know it may be disturbing (it disturbs me), the one thing that has had the greatest impact on me, was watching my closest friend die right before my eyes. It's something I never want to see again!

 Yes, watching a very close friend die right before your eyes has to be something you will never forget. If there is any justice to your friend dying, it would be that you may be able to comfort someone else sometime who has gone through something similar.