In the fifteenth century, the hospital enjoyed remarkable economic prosperity and in 1419 received a visit from Pope Martin V. In 1420 the addition of the cloister of the medical center by Bicci di Lorenzo marked a major transformation and expansion of the original building.

The addition still has a terracotta lunette depicting the Pietà by Giovanni della Robbia and clay sculpture with the Madonna with Child and two angels, attributed to Michelozzo.

In the early decades of the fifteenth century the aisles were decorated by Niccolò di Pietro Gerini with frescoes that are now partially preserved in the original locations and some were detached and placed in the living room of Pope Martin V where they now have the office of the hospital president.

In the administrative hall (room and lounge of the hospital president), which are accessed by a staircase in the Cloister of Bones, there are frescos and other works from the facade of the Church of Sant'Egidio and from other monasteries.

On the front the statue has the following inscription: "Count Angiolo Galli - that emulating the love of the ancients - the ancestral heritage linked - to hospitals in Tuscany".