Looooooong term data storage

I am wondering what the best way is to store data long term, I am specifically talking about digital photos and digital video. Now that I am a Dad the last thing I want is to loose all the pics and vids of my baby girl.
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I have an external hard drive with plenty of room, but how long will a hard drive last locked in a safe? Are DVD's a good option? It may sound odd but I would like to back up my pictures so my daughter can view them when she is 80 and pass them on down to her family. I only have a couple of pictures of my great grandparents and I would like for my daughter to have more good quality pictures when she gets older.


Thanks in advance for any help.