"An Tobar", the Gaelic for "The Well", derives it's name from "The Horse Well" which is set in rocks buried beneath the lower garden. It is believed that the well gained its name as a watering hole for local and travelling horsemen.

In the 1920's the water was piped from the well to the Parochial House, the site of which is now the car park below the current house. The over-flow from the well ran across the road through what is now the girl's primary school and Glenmisken to join the Fairy's Glen. One of the old legends referring to the well tells of a large Kerry Blue ghost dog, with red glinting eyes, named "Wollaby".

The dog was reputed to roam Rostrevor, being unable to leave as it was confined by the running waters blocking its way. These waters were the overflow from the Horse Well, the Glenstream (at the bridge) and the Ghan at Drumreagh. It is believed that Wollaby finally managed to escape his imprisonment when the Horse Well overflow was redirected to allow for the building of houses.