The Shape of the Branches of the Menorah
The menorah is very frequently employed as a Jewish symbol. Nevertheless, the authenticity of the design with which the menorah is usually depicted is a matter of question. For there are several inconsistencies between the designs generally employed and the description of this article in the traditional sources. The branches of the Menorah are one such example.
Generally, these branches are depicted as semi-circular or oblong in shape. Nevertheless, Rashi in his commentary to the Torah,  explicitly writes that the branches “extended upward in a diagonal.” Indeed, the very Hebrew word which the Torah uses to describe the branches, קנים, implies a straight line. 
What is the Rambam’s view?
Part of the confusion concerning the shape of the branches of the menorahstems from the fact that the Rambam makes no definite statement regarding this issue, neither in his Commentary on the Mishnah, nor in his Mishneh Torah. For that reason, several commentaries  were to the conclusion that he also agrees that the branches were semi-circular.
Nothing, however, could be further from the truth. The Rambam does not describe the shape of the branches of the menorah, because it is unnecessary. In both his Commentary on the Mishnah and his Mishneh Torah,  he adds drawings in which he depicts the menorah (see facsimile). And in both instances, he shows the branches as extending diagonally, in straight lines. Unfortunately, at the time the Rambam wrote these works, printing presses had not been invented. It was not until several centuries after his passing that his texts were printed, and in these printings, his original drawings were omitted.  [See more facsimiles of handwritten copies of the Rambam’s works depicting the Menorah in the same way.]
Equally clear evidence of the Rambam’s perspective can be gleaned from the commentary to the Torah written by his son, Rabbeinu Avraham. When describing the manner in which the menorah was fashioned,  Rabbeinu Avraham states: “The six branches… extended upward from the center shaft of the menorah in a straight line, as depicted by my father, and not in a semi-circle as depicted by others.”
The Position of the Goblets
Another of the points of difference between the Rambam’s conception of the menorah as reflected in the above-mentioned diagrams, and the commonly accepted design of the menorah, is the position of the goblets. To explain: There were 22 goblets in the menorah. The Rambam describes them  as “Alexandrian chalices with wide mouths and narrow bases.” In his drawings of the menorah, he depicts them as having been positioned upside down,  while the general conception is that they are standing upright.
The Source for the Misconceptions
How did these misconceptions arise? The source for the commonly accepted drawings of the menorah is its depiction on the arch of Titus in Rome. When Titus returned from the conquest of Jerusalem, he had an arch constructed in honor of his victorious army, and on that arch appears a relief which includes a depiction of the menorah.
The design on that arch is obviously an artist’s interpretation, and not an exact replica of the menorah of the Beis HaMikdash. This is reflected by the fact that certain elements of the menorah are omitted in this depiction. For example, the menorah had feet extending from its base,  and the menorahon the Arch of Titus has no feet. Similarly, the depiction contains additions, for on its shaft is the form of a sea-dragon, one of the false deities worshiped by the Romans.  Accordingly, it cannot be relied on as an accurate source regarding the design of the menorah, particularly in regard to points where it contradicts the views of our people’s leading Torah authorities.
Herein, lies another significant point: As mentioned, the menorah is often employed as a Jewish symbol. This is indeed appropriate, for our Sages teach  that the menorah is “testimony to all the inhabitants of the world that the Divine Presence rests within Israel.” How unfitting is it that instead of drawing that symbol according to its conception by Torah sages, the conception from the arch which proudly states “Judea is vanquished” is used instead!
The Outpouring of Divine Light
To return to the design of the menorah, one might ask: why are the goblets indeed positioned upside down? The resolution of this question is connected with the function of the menorah within the Beis HaMikdash. Our Sages explain  that the purpose of the menorah was not to illuminate the Sanctuary, but rather to spread its light throughout the entire world. For this purpose, the windows of the Beis HaMikdash were constructed in a unique manner, wide on the outside, narrow on the inside,  clearly indicating that their purpose was for the light of the Beis HaMikdash to shine outward.
A similar concept applies in regard to a goblet.  It possesses two functions: to receive and to pour. Turning a goblet upside down indicates an emphasis on spreading influence to others. To apply these concepts to the goblets of the menorah — their overturned position reflects the purpose of the menorah within the Beis HaMikdash, not to receive and contain G‑dly light, but to spread that light throughout the world at large.
An overturned cup is associated with happiness.  This also relates to the Beis HaMikdash which served as the source of happiness and joy for the Jewish people. May we soon experience the ultimate happiness, when we, together with the entire Jewish people, return to Eretz Yisrael, to Jerusalem, and to the Beis HaMikdash. And may this take place in the immediate future.
Adapted from Likkutei Sichos, Vol. XXI, Parshas Terumah; Vol. XXVI, Parshas Tetzaveh. Reprinted from Seek out the welfare of Jerusalem