Here's another set that I came across whilst looking for the 'post' theme a couple of weeks ago. This set showing medieval minarets was issued in 1971 for Post Day in Egypt.
The 55m shows the Al Hakim Mosque, which has the earliest surviving minarets in Cairo (wiki link).
The 20m shows the minaret of the mosque at Esna (which is in Upper Egypt, between Luxor and Aswan).
The 10m is the minaret of As Salih mosque, and the 5m the minaret of the al-Mansur Qalawun mosque (wiki link).
Thanks for visiting.