This is one of the phenomena that occurs at the The Oregon Vortex.
You can actually see and take pictures of the change in height, as is shown below.
When you have the pictures developed you can even measure the difference in height
on the pictures.
However, it is important to note that whatever instrument you use to measure with while inside the affected area
you will always measure to be the same height because the instrument of measurement
will change in size right along with you.
So don't forget your still camera!
Picture 1 - The appearance of similar height
Picture 2 - The change of height after switching places
These pictures shows two people standing on a level platform within the area,
in the backyard of The House of Mystery, close to the area's center.
Picture 1 - Without background
Picture 2 - Without background
These pictures have the potentially confusing background lines and angles of
The House of Mystery cut out. The change of height is still
just as visible without the background.