What building does the Great Scientist (supposedly...according to the description) create?
I got my first Great Scientist in a one city empire which had Library; University; Great Library and unlike the description the Great Scientist didn't have an option to create an academy or other building. [I didn't have a spare city without library or University to test if it would create a building there.]
You have to move the Great Scientist to a hex other than the city hex in your civilization to build the academy, it will overwrite any existing improvement and give you a hex you can work for the extra science.