Damn, I was hoping I was going to be the first to say that. Written language to be more specific. The ability for humans to lean from others. To transfer knowledge is by far out greatest achievement.

So, books and stuff.

Yea, I mean forget about the 400,000 people in employed, the thousands of scientific discoveries we made, and the fact that the whole thing cost less then the bailout that allowed chrysler to live for 2 more months.

Pizza.

And also, the Internet.

Wheel...Internal Combustion Engine....Alternating Current (Tesla FTW).

That's exactly it. I figured our greatest achievement would be one that is the eventul culmination of other great achievements. That's why I said the Voyager missions. I remember reading in Focus once that if mankind ceased to exist right now, in 100 million years the voyager missions would likely be the only sign that we ever existed.

If your greatest achievement is the culmination of all those before it, than it will be changing ALL THE TIME. One day, we'll put a human on Mars. Next, we'll build colonies there. Eventually, we'll find ways to travel to other galaxies. I could go on and on, but if our greatest achievement is just the most advanced piece of technology, it's going to change many times.

Language. The ability to quickly transmit information between the current generation and the next has allowed us to constantly improve.

You are correct. But I think we see it different ways, but that's ok. I think that the furthest object away from earth, the largest structures, the tallest building, the best theory, etc... Are testaments to all that mankind has achieved and how far we have come. It will change every now and then, but that's because the new technology allows us to better ourselves and that's fine.

I don't mean every time we make a slightly faster processor, we make that the best thing mankind has achieved. I mean huge symbolic achievements such as landing on the moon or building the empire state building.

Farming, harnessing electricty and the toilet.

Mathematics, since we use it to explain everything else.