This is the list compiled by the Trip Advisor. It is always highly debatable what the top ten items are in any category; similarly with this list. Do you also have other landmarks in mind which are more significant like Kimberley or the Castle in Cape Town which should be on that list? Being totally unbiased I nominated Number 7 Castle Hill Port Elizabeth for the top position. The owner of the oldest extant house in Port Elizabeth and I have something in common. The Reverend Francis McCleland was my great great grandfather and the minister of the first church in Port Elizabeth.
According to the Heritage Collection:
No 7 Castle Hill was the residence of Rev. Francis McCleland and his family. He built his parsonage in 1825. The picturesque cottage is one of the oldest remaining dwelling houses in Port Elizabeth and is furnished as a family home of the mid-Victorian period, depicting the early Settler way of life. The house was declared a National Monument in 1962 and became a museum (No 7 Castle Hill Museum) in 1964.
Main picture: Number 7 Castle Hill in Port Elizabeth