Harold is a giant flying turtle with a city on its back which first appears in its planning stage in Nerd³'s Minecraft Buildy Thing (LP) - 9, and is not completed until Nerd³'s Minecraft Buildy Thing - 16.
The initial idea to build Harold came as a combonation of suggestions from commenters Optimatum and RaiuTree.
According to Harold's internal History Musem, this is the story of why and how Harold was created:
"Our story starts 5000 years ago...
Our ancestors were in danger.
A giant Hare was marching towards our homeland.
No weapon could stop it.
No carrot, however giant, could tempt it.
Our ancestors needed a hero.
They found one.
His name was Doctor DiceIce1.
It was simple. Build a giant Turtle...
And challenge the Hare to a race.
The winner would live. The loser would die.
Construction began immediately.
"Harold" was built in three months.
On top, a town and farm to support a small group.
Inside, a swimming pool stadium for teh lolz.
The race began one fateful morning.
The Hare instantly took the lead...
"Harold" set off at a slow steady pace.
For centuries they raced.
The Hare was far in the lead.
"Harold" was far behind.
Then Doctor DiceIce1 unveiled part 2 of the plan.
A second creation, this time of a Hare.
A female Hare.
A Sexy, female Hare.
A really slutty, sexy, female Hare.
So, to cut a long story short...
...you try doing anything with four kids and a wife.
A nagging wife...
I forgot what I was saying...
Be the best you can be!
Or some crap like that.
PS. Pick up some milk.