In 1400, it carries out statuettes of prophets, evangelists and of Augustin saint for the furnace bridge of San Jacopo in Pistoia. In 1402, with a relief on the sacrifice of Isaac, it gains, equal with Lorenzo Ghiberti, the contest for the second bronze door of the baptistry of Florence. But, not wishing to collaborate with Ghiberti, Brunelleschi will not give following its project. Although recognized main goldsmith in 1404, it will be interested more in the sculpture, before turning resolutely to architecture.

In 1418, a notice of competitions is launched to equip the cathedral with Florence of a cupola; Brunelleschi presents a model, which does not convince from the start the jury; it proves the accuracy of it by building in San Jacopo Sopr' Arno a vault covered by a cupola built without clotheshanger, and it ends up obtaining the direction of the building site of Santa Maria del Fiore, again with Ghiberti, which it will manage to oust around 1426. Work of the cupola starts in 1420, whereas Brunelleschi was in addition seen entrusting by Arte della seta those of the hospital of the Innocent ones, a refuge for abandoned children, which will be inaugurated in 1445.

Taking as a starting point the cabins florentines, the architect produces on the long side of a place a gantry - into which it introduces the Corinthian order - which gives access to a unit understanding a cloister, a church and a dormitory. The bearing structures are development by the use of will pietra serena, a rock dark gray whose hardness allows the realization of monolithic columns which are detached with arcs and architraves on the white coating from the wall, process that Brunelleschi will réemploiera on several occasions. By building this gantry, the architect also thinks the place on which it opens the building: this one will be bordered by the gantry of the house of Servites of Marie, which had in Antonio da Sangallo and Baccio d' Agnolo, while its third side will be marked by the arcades of the church Santa Annunziata, built by Michelozzo.  

In 1421, Brunelleschi undertakes for the parish church of Médicis, San Lorenzo, a vault peerage-book, which will be called Vieille Sacristy after construction by Michel-Angel, in 1521, of the New Sacristy. It is one of the works of Brunelleschi which will be the least faded by additions, and the first building of the Rebirth in central plan: a surmounted cube of a hemispherical cupola, whose voûtains rest on the pendentive ones. For the church San Lorenzo itself, of which he undertakes the rebuilding in 1425, he adopts a basilical plan with three naves. The central nave is covered with a wood ceiling with boxes and is equipped with high windows; the side aisles, arched, are lit by oculus.

Covered vaults of a barrel vault open between pilasters. The square formed by the transept crossing - surmounted by a cupola - is used as measurement: it determines dimensions of the chorus, of the arms of the transept and the side aisles. The church will be finished around 1470, and it is difficult to make the share what concerns the preliminary draft of Brunelleschi and of what belongs to its successors. The basilical plan regulated on the square is also adopted for Santo Spirito, from which construction begins around 1436. The geometrical rigor is here still higher than that of San Lorenzo, but the project of Brunelleschi, too revolutionary, will not be respected. The construction of Santa Maria degli Angeli starts in 1434: the building is octagonal, with a central space and eight radiant vault-cells. The construction of this church will be stopped in 1437, and Brunelleschi, which dies in Florence in 1446, will not on the occasion to finish the building. But this central plan, undoubtedly inspired of the Roman temple of Minerva Medica, will influence Belling and Michel-Angel.  
 

Return to the antique and innovations

The first biography of Brunelleschi, due to Antonio Manetti (1423-1497), mixes picturesque anecdotes and panegyric. Giorgio Vasari in her Lives of the most excellent painters, sculptors and architects (1542-1550) takes again the process: “This man was sent to us by the sky to renovate architecture mislaid since centuries.” Brunelleschi would have gone to Rome between 1404 and 1406 with Donatello and it would be gone back there around 1417 (modern criticism also advances the date, dubious, of 1430): there, he would have studied the architecture of the ancient monuments, in order to draw some from the practical rules of construction.

But Brunelleschi, far from being satisfied to copy the antique, rehabilitates of it the vocabulary at a building which it designs like an organic whole, governed by measurements and harmonic ratios. Its knowledge of ancient architecture could also be due to the direct contact with the Romance monuments Tuscan (with Florence even, San Miniato and the baptistry, of which it is inspired for the lantern by Santa Maria del Fiore).  

Although recognized and honoured - it was buried in Santa Maria del Fiore, and was entitled to a monument with a commemorative epitaph -, Brunelleschi had to fight to impose its projects, in particular that of the cupola of the cathedral. Cosme de Médicis refused the plan of a new palate, considered to be too sumptuous. Santa Maria degli Angeli was given up, and Santo Spirito was notably modified: the vaults which were to show their rotundity outside were dissimulated by a wall enchasing them; one finally built three doors in frontage instead of four; moreover, Brunelleschi did not obtain to direct the church towards Arno, which would have created a new relation of the city with the river. Manetti charges number of the imperfections of the buildings of Brunelleschi to Francesco della Luna and Manetti Ciaccheri, who completed them after his death.  

Filarete and Manetti allot to Brunelleschi the invention of the prospect, well before Alberti codifies of them the processes in its treaty Of painting (1435). For engineer Brunelleschi, the prospect constitutes an instrument of calculation and a rational means of reproduction of the buildings. It highlights the tension fields of architecture (colonnades) and scannings of space (alternation of the vacuums and full). Around 1415, it paints two small paintings representing in prospect the baptistry for Florence and the palate of the Seigniory. It would have also taken share, in Santa Maria Novella, the graphic construction of the architectural framework of the Trinity, mural of Masaccio. The influence of these lessons of prospect will be particularly sensitive in FRA Angelico and schoolmasters florentine such as Filippo Lippi.  

The extraordinary capacity of invention of Brunelleschi appears perhaps more in its technical lucky finds that in its esthetic choices. The construction of the cupola of the cathedral requires to raise approximately seven tons of materials per day: it develops cranes and winches using endless screw, pulleys, gears and cogwheels, as well as scaffolding ensuring the safety of the workmen. According to Manetti, its experiment in the field of the clock industry was very advantageous for him. Certain drawings of Leonardo da Vinci take as a starting point its creations.  

Brunelleschi proposes a new type of luminous church whose plan is governed by the golden section, in San Lorenzo and Santo Spirito; with the hospital of Innocent, it draws up a report particular to urban space by causing the creation of the public place. It reintroduces the central plan on the basis of of the square or circle to the Old Sacristy, the vault of Pazzi, and Santa Maria degli Angeli. Its employment of will pietra serena to underline the frame of its buildings will be often taken again, in particular by Michel-Angel.

Lastly, one allots to him the project of the one of the first urban palates of the Rebirth, the Pitti palate. Its inventions mark the beginning of the architectural Rebirth inside a still medieval city: consul of Dieci di Balia (the council of the government), Brunelleschi takes part in the administrative life of Florence, girded city of walls, with compact urban fabric, and from where emergent the great Gothic architectures, of which the bell-tower of Giotto.

But if the cupola of Santa Maria del Fiore - “enough vast to be able to cover with its shade all the inhabitants of Tuscany”, according to Alberti - is more reappearing by his technical innovations that by its slightly pointed form which does not dissociate it clearly ogival style, it expresses a direction of new space and reorganizes the aspect of the city of Médicis symbolically to affirm of it supremacy vis-a-vis its rivals, Milan, Venice, Pisa, His, Lucques.