The Neverending Story (Die unendliche Geschichte) by Michel Ende was published in 1979, and mostly takes place in the country of Fantastica. J.R.R. Tolkien’s The Lord of the Rings (which mentions and describes Saruman and Orthanc) was published in 1954, 25 years earlier.

Fantasia was a Disney animated movie from 1940, but did not, as I recall, feature a wizard’s tower.

Fantasia was a 40s Disney cartoon with a famous Mickey scene