Intersection of Ithan Avenue & Conestoga Road, Rosemont, PA 610-525-8400 Turn right onto Bryn Mawr Avenue. Turn right onto South Ithan Avenue. Stay on Ithan for approximately 2 miles. Agnes Irwin is on the right. There is a light at the intersection of Ithan and Conestoga. The school is just as you cross Conestoga. You’ll probably need to park on Ithan Avenue because the lot is usually full.