The obelisks of Heliopolis were sacred pillars in the temples there, about 5 miles northeast of Cairo. The LORD sent Nebuchadnezzar king of Babylon to break the obelisks.
(The ESV Study BibleTM, English Standard Version (ESV) by Crossway Bibles, 2007. Page 1448-1449; Jeremiah 42:8-13)
The sun god Re of Heliopolis.
(https://www.memphis.edu/hypostyle/meaning_function/amun-re.php)