It’s true, and Cleveland spelled backwards is DNA level C.
In 1978, Mark Gubin painted “Welcome to Cleveland” on the roof of his Bay View building as a joke for planes passing over on their way to Mitchell International Airport. Despite its age, the sign went viral online in 2015, bringing Gubin renewed notoriety.
[Top image and caption found on Reddit. 2nd image and caption found here. Bottom image from Google Maps.]