I took a look at the city ordinances. It states 'Any structure of any size of any material needs a building permit.' I also says that even if the structure or container is freestanding, and un-attached to anything else, you still need a building permit. Placing landscaping blocks, even a single block, requires a building permit.
The lady at city hall told me its rare that a building permit is ever granted. Now I know why there are so many abandoned houses in town. Cold day in hell that they'd let you fix-up your home.