This place are mainly for a few persons: Uesugi Kenshin 上杉謙信, Uesugi Yōzan上杉鷹山 and Date Masamune 伊達政宗.
Date Masamune was born here so there was a stone recording this.
Uesugi Kenshin originally had nothing to do with this city. When he marched to war with other generals, he passed away suddenly (some says that was due to heart attack) and he was buried in this castle. Therefore, his tomb was here and the people set up a shrine for worshiping this god of war. There is a statue of him too. (2nd and 3rd pictures)
Before I came to here, I know nothing about Uesugi Yōzan. Now I know that this guy is really something. He was the mayor of this city and he governed this city so well that JFK once said that he respected this guy most.