Trying to build a grid of images.

http://corazonhome.com/
ata 3.7.3 wp 3.3.1
I am trying to create a grid of images 4x4 with no space between them.
The top row is my attempt with css. I don't know why they are stair stepping like that. The bottom row is my attempt with tables. I can find no reason for the spaces between the cells.
I don't want to use a plugin because it is not a gallery or portfolio. I just want image links to pages.
help?