Paolo Guinigi very engaged in order to ensure the pacification of the city and a return of refugees. The economy was raised and the tax system reformed. Foreign policy was handled cautiously acknowledging the small size of Lucca with respect to the formation of regional Italian States. The power of Paolo Guinigi was preserved also because of his arranged marriages such as that one with Ilaria del Carretto. Ilaria, unfortunately, died at an early age in 1405 and Paolo Guinigi commisioned the sculptor, Jacopo della Quercia, the famous marble sarcophagus, kept in the Cathedral of St. Martin nowadays. The tensions and wars between Venice and Florence United, Milan, Filippo Maria Visconti's greatest ally, led to a crisis that allowed the Florentines the siege of the city in 1429. In 1430, an internal conspiracy deposed and exiled Paolo Guinigi.

Returning to the Republic, Lucca gained in peace with Florence 1438 backed by military aid of the Visconti. The territorial situation was however compromised: the Garfagnana had been invaded in part by the Estensi, Barga, Pietrasanta occupied by Genoese and then by the Florentines. However the small Republic, now reduced to territorial City-States, prosperity returned in the second half of the 15th century through international commercial activities such as the production of fine silk fabrics. The silky industry went into crisis in the sixteenth century, when competition with other European centres led to overproduction causing the weavers themselves.
Thanks to merchant contacts with Northern Europe, the city of Lucca welcomed the Protestant Reformation: the presence of "heretics" in almost all the major families of Lucca was tolerated and minimized.

But the fear of a crusade by Pope Blessed Florentine urged citizens to a voluntary exile to Geneva and other northern cities. The Republic of Lucca proved decisive in maintaining intact its jurisdiction without interference of the Church fit in and, subsequently, to the establishment of the Inquisition.
The exodus of some of the major families of Lucca town impoverished capital, human resources and culture. From 1556 the reformation of Gonfaloniere Martin Bernardini made public charges only accessible to families of more proof of ancestry oligarchic impression taken by the Republic of Lucca. From the urban point of view, between the end of the fifteenth and early sixteenth century, most of the palaces of the city aristocracy was renovated according to the canons of contemporary Tuscan architecture and medieval towers in abandonment were decimated and destroyed.

These changes are integrated into the urban fabric citizen who maintained volume and layers.