I know it's hard to tell from this picture but what you are looking at is a common form of security in Taiwan. It's broken glass shards placed along the top of outer walls of houses, government offices, and even schools.
On the one hand it seems like a nice way to recycle, but it also seems like difficult and dangerous work to do. not to mention easier to get around than other security. However I guess it gets the job done as the point of any security isn't to be the safest, it's to be safer than others so thieves will concentrate on the easier targets.
The buildings that do have this are all ones that are over 50 years old. Meaning whenever I see this glass, I ponder what the situation must have been to cause people to put this up. I'm sure the glass isn't that old, so there must have been some time between then and now when people were worried enough to put broken glass shards on top of their walls.
Perhaps one day I will find out the truth, but for now I enjoy being able to make up my own stories why this was done.
