What is the font of the slogan on Tianan City Gate?

The font of the slogan on Tianan City Gate is Song Dynasty. These two huge slogans on the Tiananmen Gate Tower are written in solemn and generous Song-style artistic calligraphy, each of which is 2 meters square. Its prominent position, long preservation time, and it is considered a model of Song style artistic calligraphy were all unexpected by the original calligrapher.

Zhong Ling wrote for it

It was the first time that Zhong Ling wrote such large artistic calligraphy. He was very rigorous and serious and wrote for two days. At the end of September 1949, two huge slogans were hung on the Tiananmen Gate Tower.

On the National Day of 1950, these two traditional Chinese slogans were changed to "Long live the Communist Party of China and long live the great unity of the people of the world." Later, the slogan was rewritten to promote simplified Chinese characters. After this time, these two huge slogans have not been changed for decades.