Spatial Intelligence is all about measuring how well you can visualize or figure out visual problems and circumstances. In here, you only use your eyes and the mind.
Spatial Illusions are very very tricky and requires a person not to be only smart but also to be alert because it involves a lot of mind tricks. There are a lot of spatial illusion examples, but the most common one are, as what we call, OPTICAL ILLUSIONS.
Here is a video of the top 10 best optical illusions of 2014 by the Youtube channel, Good Mythical Morning.