[3] This feeling finally turned into practice in 325 AD with the First Council of Nicaea in Bithynia where the 300 or more of bishops gathered there established that "in every city houses called Xenodochi and hospices for pilgrims should be built, for the poor and for the sick.

[5] After the First Council of Nicaea the Church was strongly committed to the creation of brephotrophs for exposed infants, orphanages, gerontocomia for the non self-sufficient elderly, as well as Xenodochi and Nosocomi, for pilgrims.

This pilgrimage lasted centuries; in that period Rome enjoyed such a fame that at least ten sovereigns are known to have come ad limina Apostolorum[8] the first of them was Cædwalla, King of the Western Saxons (685-688).

Pope Leo IV looked after the reconstruction of the Church of Santa Maria in Saxia and of the Schola of the Saxons, in which many kings of Northern Europe, like Burgred of Mercia, or the Prince Alfred the Great, found rest after an exhausting journey.

A prosperous period followed; but, due to historical events such as the Norman invasion of England in 1066 and the beginning of the Crusades, which routed the crowds of pilgrims towards other destinations, the institution declined and just maintained its name.

Furthermore, on November 25, 1198 he approved and recommended the Order of the Hospitallers, through the bull “Religiosam vitam”, by which he welcomed Guy de Montpellier and the institution he had founded under the protection of the Vatican.

Thanks to the consecration of this new institution, Innocent III created a statute of rules for the Order of the Hospitallers, who was entrusted with the management and the safeguard of the Hospital, under the control of Guy de Montpellier.

He built in his native town a Hospital House, that rose in the area now called Pyla-Saint-Gely, and founded a regular order of Hospitallers Friars (1170), consecrated to give assistance to infirm, abandoned children and whoever needed help and cares.

By giving rise to the Holy Spirit organization, Guy wanted that ”the assistance and care were free from the cold-heartedness of a paid service, and raised up to the degree of a sacred duty, deserving to be compared to the pureness of the Apostles and early Christianity age”.

With the 1198 bull he confirmed the foundation of the Hospitallers and placed them under his protection, together with all the French branches and the ones that were rising in Rome, such as Santa Maria in Trastevere and Sant’Agata on the Via Aurelia.

Sixtus IV (1471-1484), visiting the Hospital soon after his election, described it: “the falling walls, the narrow, gloomy edifices, without air and whichever comfort, look like a place intended for the captivity rather than health recovery”.

Finally, the importance of the Anatomical theatre can not be overlooked: it summoned such artists and scientists as Michelangelo, Leonardo da Vinci and Sandro Botticelli, who reproduced the façade of the hospital in the background of the fresco “Jesus cleansing a leper”.

In 1478, the walls of the Corsia were frescoed with a frieze made by more than fifty scenes, depicting the origins of the hospital of Innocent III and the most important episodes of the life of Sixtus IV.

The complex of the Ospedale di Santo Spirito lies over an area that, in ancient Rome, was occupied by the villa of Agrippina the Elder (wife of Germanicus and mother of Caligula): in some rooms below the Corsia Sistina, remains of opus reticulatum walls, mosaic floors, carved marbles and frescoes are still visible.

The central arch of the lower loggia hosts a fountain erected by Paul V as a decoration for the Palace of the Vatican and later moved to the Palazzo del Commendatore by Alexander VII.

On the right of the main entrance are the Accademia Lancisiana and the grand staircase, giving access to the first floor of the Palazzo and to the upper loggia, which shows a plaster impression of a low-relief by Antonio Canova depicting a lesson of anatomy.

The walls of the upper loggia are entirely decorated with frescoes commissioned by Cardinal Teseo Aldrovandi to the painter Ercole Pelillo from Salerno; they show landscapes, panoplies and grotesques.

The loggia gives access, through a double doorway, to the Apartment of the Commendatore, consisting of many rooms decorated with magnificent tapestries, ancient furniture and sculptures, among which a Virgin with the Child by Andrea del Verrocchio.

Each scene simulates a tapestry bordered by draperies, on which the coats of arms of Santo Spirito, with its typical "Cross of Lorraine", and of the Aldrovandi family are alternately represented.

[22] The Room of the Commendatore, as well as the upper loggia, give access to the Biblioteca Lancisiana, founded in 1711 by Giovanni Maria Lancisi, an eminent scholar and the doctor of Pope Innocent XI, who made this library the heart of his project for the promotion of scientific culture.

The library also conserves 373 valued manuscripts from 14th to 20th century, among which two parchment codices with Latin translations of texts by Avicenna and the well-known Liber Fraternitatis Sancti Spiritus.

A little window, located behind one of the walls of the library, opens up at the level of the frescoes of the Corsia Sistina: it allowed the various Commendatori who managed the Institute to check up on the staff responsible for the care of the sick.