Why was Mashhad chosen as Khamenei's final resting place?

Former Iranian Supreme Leader Ayatollah Ali Khamenei had reportedly expressed his wish to be buried in the Iranian city of Mashhad. Born there in 1939, Khamenei spent his childhood and received his early religious education in Mashhad. The city is also home to the Imam Reza Shrine, which is one of Iran's holiest sites for Shia Muslims.