The seven-branched Menorah is described in great detail in the Torah (Exodus 25:31-40). Even so, the Torah omits one very basic detail which has led to divergent opinions on the matter: whether the Menorah's branches were straight or curved.
Others argue that this surely could not have been the Menorah of the Sanctuary since the base is nothing like we would expect the real Menorah to have. First, its two-tiered, octagonal design is a novelty. Second, archeologists have concluded that some of the creatures depicted on its panels are sea serpents, and Jews would not have allowed such heathen images in the Temple.