15 at Huntingdon Valley. The new tee box extended this par 5 and made an oblique tee shot out of a former straightaway hole.
I believe this was a part of the JB McGovern/Donald Ross modifications made for the pending (but never realized) change in right-of-way for Welsh Road.
It was also made possible by moving the 14th green up the hill and to the left of its original position, which, IMO, is another improvement.. even if it changed the nature of the fairway hazards from oblique heroic to oblique penal.
Though I have no frame of reference, how about the 10th-13th at Merion? The 1st hole?