The Opera Pia Purgtorio ad Arco ONLUS is a secular charity institution and it owns the Museum Complex of Santa Maria delle Anime del Purgatorio Ad Arco. This institution has more than 400 years of activity and it is one of the older still existing Charity Institution; its origins date back to the XVII century to give assistance to the poor people of the city center of Naples. Particularly, it was founded in 1605 as a Counter-reformed institution, by members of Naples aristocracy. The institution has kept the mission indicated by its founders: to help poor and sick people and to boost activities and masses for the Purgatory Souls in the Church of Santa Maria delle Anime del Purgatorio Ad Arco. The Museum Complex includes a Historical Archive, managed by the Friends of the Archives Association, where important documents related to the history of the institution are preserved. The institution was founded thanks to the spontaneous donations of Neapolitan citizens, as it is written in article 1 of the 1875 founding statute, and it was recognized by Pope Paul V with an Apostolic Act dating October 15th 1606. The Pius Congregation originally used to gather in the Church of Sant’Arcangelo a Segno, then in Santa Maria della Rotonda and finally in Sant’Arcangelo a Nilo; afterwards, in 1616, with the increasing of the donations, it was decided to build a new church for the Congregation, with a project by the architect Cosimo Fanzago and it was dedicated to the Souls of The Purgatory. The benefits for the members of the Congregation included the possibility to be buried in the Church cemetery and to have masses in occasion of their death. To the celebrations organized for the members of the Congregation, were associated also the daily celebrations for the souls of all their relatives. Moreover, thanks to donations of the citizens, celebrations were organized for the souls of poor people that had no means. In addition, the charity activities promoted by the Congregation included donations for poor girls in order to help them to get married and for poor children. In 1862, with the Crispi Law, the all the Italian “Opere Pie” were compared to semi-public charity institutions and in 1890 they were transformed into public charity institutions. The Opera Pia Purgatorio Ad Arco is still active and the members of the Congregations are involved in the field of charity, assistance and religion.