Amon Sul was the name of the watchtower built by Elendil on the hill of Weathertop. Commanding views of the surrounding areas of Arnor, it also contained a Palantir which was used to communicate with Gondor.
Park at the parking coordinates (south end of the pullout before starting down the hill towards Rye), and hike south along the fence to the gate, then go through and up to the top of the hill. It is a mild climb, but at the top the view is spectacular.
I had planned to call this cache something else, but planted it in the midst of a rain/sleet storm. With the clouds rolling in and out, I thought that Weathertop was an appropriate name.
FTF may take the cool Alien Geocoin. Be sure to make note of the letter hidden in the cache log. It may come in useful someday.