Why did he build Mizbechos in Beis Hashem?
Malbim (Melachim II, 21:4): They were to Hashem. He wanted to show that also in Avodas Hashem there are separate Avodos. This denied Hashem's unity 1 !
How does this deny Hashem's unity? Hashem commanded us to build two Mizbechos! Shlomo built additional Menoros and Shulchanos, and some say that all were used for the Avodah (Menachos 99a)! (PF)
Why does it say "Asher Amar Hashem bi'Yrushalayim Yihyeh Shmi l'Olam"?
'Rashi': The verse 'complains' about Menasheh. Hashem wanted His name to rest there!
Malbim (Melachim II, 21:4): This explains Menasheh's intent. Hashem chose Yerushalayim for His Shechinah and conduct of the world. Menasheh wanted to show that He has helpers to run things outside.
