It’s located just outside Fort Amol. Start at Fort Amol Wayshrine, enter Fort Amol and follow the road going northeast. As soon as you cross the bridge, turn 180 degrees and go down to the river bank, next to the base of the bridge. Skyshard is right there.
Near the eastern bridge to Amol, second bridge East of the Amol Wayshrine, along the river.
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