In cities, Heliopolis (TR:31), hieroglyph "", originally called An, Anu, Junu, Iunu, Heliopolis (Greek), On (Hebrew), aka the “city of the sun”, was a prominent city of ancient Egypt, which arose to power in c.2800BC, being the foremost religious center, wherein the so-called Heliopolis creation myth was promulgated, centered around the Heliopolis ennead or paut (group) of nine gods, with Atum and later Atum-Ra as the supreme god.
The main hieroglyph, supposedly, for Heliopolis is the following: 
which, according to Wallis Budge, is a pillar or obelisk with a cross on it, the water symbol or god Nun symbol, and a sun with a cross in it and or a sun inside of an eclipse, and a half-circle, which is bread. (Ѻ)
The following, from Wallis Budge’s Egyptian Hieroglyphic Dictionary (1920), shows the various hieroglyphs for the Egyptian city of An (or On, Anu, Junu, Iunu), renamed later by the Greeks as “Heliopolis”: 
The following are related quotes:
“The ancient Egyptian cult center Junu, named ‘On’ in the Hebrew Bible, was renamed ‘Heliopolis’ by the Greeks in recognition of the fact that the sun god Ra (Helios in Greek) presided there. Junu is mentioned in the Pyramid Texts as ‘House of Ra’.”
— Karl Luckert (1991), Egyptian Light and the Hebrew Fire (pg. 41)
1. Anon. (2016). “The Story of Osiris – Ancient Egyptian God Documentary” (Ѻ), YouTube, Ancient World History, Dec 23.
2. Budge, Wallis. (1920). An Egyptian Hieroglyphic Dictionary, Volume Two: With an Index of English Words, King List and Geographical List with Indexes, List of Hieroglyphic Characters, Coptic and Semitic Alphabets (pg. 958). Cosimo, 2013.
● Heliopolis (ancient Egypt) – Wikipedia.