The "bridge" extends from Promontorium Lavinium to Promontorium Olivium, and is visible at sunset but not at sunrise; try for it about four nights after full moon. The easiest way to find it is from Proclus, the prominent crater near the eastern point of diamond-shaped Palus Somni (which stands out as a dark highland area adjacent to Sinus Amoris).
On 6/11-12/98, I observed the area of Promontorium Lavinium and Promontorium Olivium with a VX102 varying from 111x to 263x. This is a feature which will probably require high magnification to see; I couldn't make out much detail at 111x, and the area was much clearer at 200x and 263x despite having to wait for instants of steady air where the image would briefly sharpen enough to discern any detail.
Even so, the connection between the two promentories did not look like a bridge to me; perhaps like a dam, with buttressed walls. But the area of bridge was still half a day away from sunset, so perhaps I was too early. I'll try again next month.
On November 14, 2000, 1:17am & 1:45am PST Bill Arnett caught several images of the O'Neil's Bridge area in nearly perfect light.
This area looks much different (and better) under these lighting conditions than the representation in Rukl's atlas.
It was early morning in this area, but the article was about the appearance of this area at sunset. There is no illusion of a bridge under these conditions.
In morning light, all of Yerkes is much more apparent, as is its more ghostly neighbor to the south, Lick.
The problem is, other readings differ with Alter. There seems to be some consensus that the brightness is caused by a combination of underlying materials being thrown up, and possibly some alteration they undergo in the high temperatures of impact -- but it may just be that the impact took place where a deposit of unusually light colored material was waiting.
There is further conjecture that the exceptional brightness of some craters is due primarily to the youth of the crater, and that there is little variation in the brightness of the ejecta in major regions of the moon. It's worth noting that the number one bright feature, Aristarchus, is almost half way across the moon but located at the edge of a plateau and mare material, which is not unlike Proclus.
They both have rays, but Proclus has the more spectacular, and strangest. There is a large gap in the system in the direction of (or defining) Palus Somni.
Another young crater, Tycho, has a similar gap in the direction of mares Nectaris and Fecunditatis, with the exception of a single large ray that bisects them (roughly).
So: it's not entirely clear why the crater is so bright, but there's some info that might help you think about it and draw your own conclusions. Palus Somni and Proclus are a truly odd feature; Alter thinks the marsh subsided subsequent to the impact, and that makes sense, but why "sinking" would make it darker is unclear, unless this were from some baking process (or other factor I'm not up on; Alter often does not explain himself...)
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