This is how to make a bridge.
66 stone stairs
Put 3 parellel cobblestone 20 blocks apart.
Pile it up to 4 layers high
Put upside down stone stairs where they face each other
Put a cobblestone block on top of the stair.
Repeat 5 times
Fill the blanks
Put stairs on the sides.
Place stairs one block on the sides under the bridge.
Fill the blanks under the bridge.
Build like a pyramid but take out adjacent nonsidetouching blocks.
Build to the ground.