Building question about ramps and platforms?

[stingo1]

Is there a key you have to press to make one building piece snap to another? I wanted to build a bridge across a river to a small island but I only got as far as building the ramp (stairs). When I tried to build a platform next to it, it wouldn't align to the ramp, it just sat at this odd angle on the ground since the ground wasn't level.

[lMatteyl]

In my experiences you can't get platforms to snap to eachother on the same plane, all you can do is snap it on top. I tried snapping a few together to create a wide raised platform to make a base on top of but i had to lay down each piece separately, and with the differences in terrain it was impossible to get them all leveled equally.