The large mural on the short entrance wall dates back to the 1847 project but was made almost twenty years later by Tommaso Minardi who depicted the Mission of the Apostles, the last great religious subject with a strong doctrinal content commissioned by a pope for the Quirinale. It was painted in 1864, when the kingdom of Italy had already been proclaimed for three years but the new state had not yet annexed the Veneto, Friuli and the Papal States.