Between Kilmashogue and Tibradden Mountains lies Kelly's Glen. A spa was discovered here around 1748 but its distance from the city and the difficulty in getting to it meant it never became popular. On the south-eastern slopes of Kilmashogue, in the saddle between Two Rock Mountain, is a ruin known as Calbeck's Castle. Despite its name, it is a small dwelling house built to accommodate visitors to the spa. Built around 1800, it had fallen into ruin as early as 1821. The lands around this area were owned by a Councillor Charles Calbeck, a landowner who made considerable investments in his lands, planting trees, building roads and bridges and improving drainage. The two bridges built by Calbeck have inscriptions dedicated to his sister Sophannie.