The Pantheon is probably one of the most drawn buildings of the history of architecture, with a symbolic weight that affects many aspects of architecture. Of all remains of Ancient Rome, this is perhaps one of the most emblematic buildings, entirely preserved and without many alterations. Its formal clarity, the logic of its constructive system and the symbolic content of its design have been valued.… Brunelleschi discovered how to build the dome of Santa Maria del Fiore in Florence mostly.whilst studying its oculus (the skylight), without the need for costly support belts. And drawing its interior, Rafael understood the correct way to represent Ancient architecture.

Clearly, the interest in the Pantheon is related to the interest in the Ancient architecture of Rome, started in the Renaissance. Such interest began with the literature and studies of Petrarca and Boccaccio. When Petrarca went to Rome (in 1337)to see the site and the buildings of Ancient Rome, in order to learn directly what was mentioned in the writings of Cicero, he found a city that did not know its own age. He desperately came to say “who is more ignorant of the history of Rome that the Romans themselves? ... Nowhere else in the world is Rome less known than in Rome” (in Trionfi e canzoniere, 1494).

It is usually accepted that these architects considered the architecture of Ancient Rome as the model to copy and learn from, par excellence. This is not literally true because Baroque architects also took it as a model and so did the neoclassic ones, and each of these architectures are very different from the other. This happens because who copies, at least if he does it in an intelligent way, always selects and values before copying. Everyone sees in Antiquity what he is searching for and what makes sense him. Thomas Browne, a seventeenth century writer, said that “there is no man alone, because every man is a Microcosm, and carries the whole world about him“ (Religio Medicis, 1642). Otherwise, we could not understand that the same model has served the Renaissance, the Baroque and the Neoclassical.

And neither the ones of the Forum Transitorium, which they had in Rome. But the baroques yes.
 

The Renaissance and Baroque architects worshiped Vitruvius and the architecture of Ancient Rome, but they knew they had flaws, that not all models were equally good and that they should choose well. The ruins of Antiquity have always been there, unchanged, so that everyone could take what they wanted. And this is the way it has been done.

This is one of those drawings, by Francesco di Giorgio Martini (1439-1502).

The problem is that, intentionally or not, the drawings did not correspond with reality. This drawing of Giorgio Martini has two attics, a different orientation of the aedicula and the skylight is missing

It is said that when Raphael was commissioned to be in charge of St. Peter’s works after Bramante's death, he tried to find a useful way to represent the interior space of the dome he had to complete. And so he went to draw that of the Pantheon and saw that it could not be represented by means of perspectives, because the resulting images were only partial, never a whole picture. From this and other similar experiences, he wrote the famous letter to Leon X in 1519, recommending a listing of all the ancient architecture, representing it in plan, section and elevation.

The difficulty of representing this space by a perspective remained a challenge, one that Giovanni Battista Piranesi (1720-1728), among others, tried to solve.
 

But this solution meant to go outside the interior space.
 

The most importantly, by the extent it wants to cover, is perhaps that by Sebastiano Serlio, who -as could not be otherwise- drew the Pantheon as well, but now in plan, section and elevation.

Desgodets travels to Rome by boat, along with some pensioners of the Academy. During the time of Louis XIV, the figure of the pensioned by the king was created, according to which a student of proven abilities was sent to Rome to complete his studies. The ship in which they were travelling was captured by Tunisian pirates, and they remained sixteen months as prisoners before reaching Rome.

Desgodets accomplished the drawings of the 3 different types of capitals in the porch, the 3 interior ones and the 3 of the altar, besides the cornices, the door and the wall.

The study allowed proving that there was no such thing as consistency in the proportions of Antiquity: that was a myth. And what was more serious: it questioned Palladio’s drawings. This was a problem for French intellectuality, born out of an absolute monarchy, which had converted a matter of taste, trend or sensitivity (always arbitrary), into an unquestionable norm. The members of the Academy judged the work negatively, firstly, because it questioned the values upon which its credibility stood; secondly, owing to the excess of measurements in the drawings and thirdly, by the author’s youth.