That's not a wall you get rid of. Go through the sewer, which you will find back to the left and then a ladder. Also you might want to use a different site to post images that one places an ad right over the image.
I thought the outside of that building's wall looked like a solid wall as well, so I added the sign saying come own in. However, you can blow up the sign.... :-) But yeah there's a ladder to get over that wall, but I thought you were meaning to get into the room behind the wall, which is through the sewer.