The Monastery of Serra do Pilar has been a Cultural Heritage of Humanity site since 1996 and provides an unequalled view of the city of Porto. Its construction began in 1538 and it was completed in 1670. It housed the Augustinian Friars of the Monastery of Grijo until it became occupied by the Liberal army during the Civil War of 1832-1834, during which it was damaged. The Royal Brotherhood of Nossa Senhora do Pilar, established in 1834 and, later, the Group of Friends of the Monastery of Serra do Pilar, created in 1925, helped save the monastery.
The church with its circular floor plan is unique in Portugal, as is the Cloister, which is also circular and is lined with 36 Ionic columns. It currently houses North Heritage. In the cloister, note the statue of D. Afonso Henriques, by Soares dos Reis, which is the plaster version of the one in bronze at the Guimarães Castle. It is worth taking the guided tour which includes a climb to the dome. It's a 100 steps to the circular terrace that surrounds the dome of the church, but the panoramic view over Porto is spectacular.
Serro de Pilar is part of the UNESCO World Heritage site Historic Centre of Oporto, Luiz I Bridge and Monastery of Serra do Pilar.
References:The Temple of Edfu is one of the best preserved ancient shrines in Egypt. It was built in the Ptolemaic Kingdom between 237 and 57 BC.
Edfu was one of several temples built during the Ptolemaic Kingdom, including the Dendera Temple complex, Esna, the Temple of Kom Ombo, and Philae. Its size reflects the relative prosperity of the time. The present temple initially consisted of a pillared hall, two transverse halls, and a barque sanctuary surrounded by chapels. The building was started during the reign of Ptolemy III Euergetes and completed in 57 BC under Ptolemy XII Auletes. It was built on the site of an earlier, smaller temple also dedicated to Horus, although the previous structure was oriented east–west rather than north–south as in the present site.