Why is there a horizontal line missing from the wall of Dali ancient city?

The word "Dali" at the south gate of Dali ancient city was inscribed by Guo Moruo in 196 1 year. Because Guo Moruo is a famous calligrapher in China, Dali is written in cursive script, and cursive script is written by Lian Bi, so it looks like a horizontal line is missing, which is very common in calligraphy. For the sake of beauty, many calligraphers write running script, cursive script and cursive script in Lian Bi.