What shape were the branches on the Menorah in the Beit Hamikdash? I have seen the diagram by the Rambam where he depicts it with angular branches. I am looking for sources in halacha (i.e. sources other than the Arch of Titus) for the rounded-branch version of the menorah.
There are two main opinions, one by Rashi saying that are straight lines going up at an angle, seen also in the Rambam on the Mishna and R' Abraham his son. See sources:
רש"י על התורה שמות כה, לב. והציור בפירוש המשנה לרמב"ם מנחות ג, ז. ודעת ר' אברהם בן הרמב"ם בדעת אביו. וכן כתב העזרת כהנים מידות ד, ז.
The other opinion is the Ibn Ezra, and it is the one accepted by Rav Ariel and the form used by Machon Ha'mikdash (דעת הראב"ע על התורה שמות כה, לב):
וששה: טעם קנים עגולים ארוכים חלולים
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Rambam and Rashi both agree it was angular. The Lubavitcher Rebbe suggests an answer as to why the arch of Titus etc. are round. It is like we say in ve'al hanissim on Chanukah "v'hidliku neirois bechatzrois kodshecha" (and they kindled candles in the courtyard of the temple). From here we see there were other menoros in the Beis Hamikdash. The actual one was angular but no one saw it since it was always inside. The ones that everyone saw (and the one Titus might have taken) were the ones outside and they were round.
Another answer I saw was that it was one of Solomon's menoros as he had ten.