RATHGAR, a townland in Rathfarnham parish, Rathdown barony, Dublin county, 3 miles south from the General Post Office, Dublin. Population 745, inhabiting 125 houses. It is situated midway between Rathmines and Roundtown on the road to Rathfarnham and Tallaght, and has sprung up within the last twenty years. In 1825 there were but 2 or 3 houses and cottages on the road.

It is now one of the most pleasing outlets of the metropolis, studded with handsome terraces or detached villas, and several pretty avenues diverging from the centre, and leading towards Harold's-cross, the river Dodder, Roundtown, and Upper Rathmines. On the site of Rathgar lodge, stood the ancient castle of Rathgar. Near the Dodder, until very lately, there were extensive calico printing works, of Messrs. Waldron, worked by steam and water wheel power, and giving employment to a great number of persons. Close to the cross roads are extensively worked quarries of calp limestone, which is chiefly raised by blasting.

There is a Post Office letter receiver established on Rathgar-road.