In 1962, in commemoration of the centennial of the Martyrdom of the 26 Saints of Japan that occurred on Nishizaka hill, the Memorial Relief of the Martyrdom of the 26 Saints of Japan was constructed concurrently with the adjoining Saint Filippo Nishizaka Church. The Memorial Hall that stands quietly behind the life-sized bronze statues of the 26 saints is divided into two themes - things handed down from Christian times and things created today in order to clarify history. It introduces the history of Christianity from the time of Saint Frances Xavier's visit until the Meiji period. Exhibitions include a letter by the priest Nakaura Julien from the Tenshou youth facility, letters addressed to Portugal's King John III from Saint Francis Xavier, the record of the battle of Shimabara, the Maria Kannon sculpture, and a bronze Pieta from the 16th century, as well as frescoes and Japanese paintings.

The museum is dedicated to the history of international exchange in early-modern Nagasaki, the only port open to foreign trade during Japan’s era of national isolation. A vast collection of documents, art pieces and traditional crafts showcases Nagasaki’s unique history and culture, from the arrival of the first Portuguese ships and the introduction of Christianity to relations with Korea, China and the Netherlands. The museum also features a partial reconstruction of the Nagasaki Magistrate’s Office, a government agency from the Edo period that once stood on this site. 

Oura Cathedral is the oldest wooden church of Gothic architecture existing in Japan. It was built in 1864 by a French missionary, and was thus known by the people of Nagasaki at the time as the “French Temple”. This church was dedicated to the 26 martyrs who had been executed on Nishizaka Hill; the bronze statues in Oura Cathedral and on Nishizaka were built to face each other. This church has been designated as a national treasure. One important story of this church is the “Discovery of the Flock”. In March 1865, hidden Christians from Urakami came to the cathedral and told the priest, Father Petitjean, that they were of the same faith as he was. When the Pope at the time heard the story of the Christian faith that had survived the centuries of harsh persecution, he was greatly moved and declared it to be the “Miracle in the East”.
Pope John Paul II visited this site in 1981.
This church was replaced with Urakami Cathderal as the Cathedral of the Nagasaki Archdiocese.
In 2016, it has been recognized by the Vatican as a Minor Basilica for its historical value.