No século XIX, foi usado como uma galeria de exposições para obras antigas reunidas de várias coleções e terminava na Tribuna, onde as esculturas de Michelangelo puderam encontrar acomodação, resultando em uma rota unificada que termina no centro da Tribuna, onde Davi é colocado sob uma cúpula que assume a forma de um halo.
O nome da Tribuna vem dessas quatro impressionantes esculturas de nus masculinos, muitas vezes chamadas de Escravos, Prisioneiros ou Cativos. As obras foram iniciadas pelo próprio Michelangelo para um imenso projeto de túmulo para o Papa Júlio II della Rovere. A encomenda original data de 1505, antes de ele receber a Capela Sistina em 1508; a intenção era que fosse a maior tumba da história cristã, com mais de 40 figuras. Na verdade, os quatro prisioneiros foram projetados para pilastras no nível inferior de uma enorme tumba independente projetada para o centro da antiga Basílica de São Pedro, em Roma.
Michelangelo levou vários meses para realizar essa tarefa específica, buscando o mármore de qualidade superior nas pedreiras de Carrara; ele escolheu pessoalmente cada bloco que considerou digno e o marcou com três círculos. No entanto, no ano de 1506, ele parou de trabalhar nela porque o Papa Júlio não tinha dinheiro suficiente para pagar por essa grande obra, o que também o distraiu de outros trabalhos, como a reconstrução de Roma!
Após a morte do papa em 1513, o primeiro projeto foi reduzido para proporções menos grandiosas, com outras alterações em 1521 e novamente em 1534, quando foi decidido retirar os prisioneiros do projeto e enviá-los de volta para Florença.
Agora, depois de quase 40 longos e tempestuosos anos, a "tragédia do sepulcro" chegou ao fim. Foi nessa época que Michelangelo criou algumas de suas esculturas mais famosas para o túmulo de Júlio II, entre elas o Moisés (por volta de 1515) e agora muito reduzido monumento funerário, que hoje se encontra em uma igreja de São Pedro pouco conhecida em Roma - San Pietro in Vincoli. Michelangelo tinha em mente uma tumba na qual a câmara seria pintada com figuras do Antigo e do Novo Testamento, juntamente com representações alegóricas das Artes e das Virtudes prevalecendo sobre os Vícios. Segundo ele, seus "Prisioneiros" significavam a Alma presa à Carne, escravizada pelas fragilidades humanas.
Quando o artista morreu, quatro dos prisioneiros foram encontrados em seu estúdio, e seu sobrinho os presenteou ao Duque Cosimo I de' Medici, juntamente com a Vitória, atualmente no Palazzo Vecchio. A gruta foi ladeada, em 1586, por Bernardo Buontalenti, com esculturas nos cantos de Boboli (cenário expansivo da Gruta da Anunciação, enorme ator dos Jardins), Palazzo Pitti (fundo localizado em Vincenzo, semelhante a um ser humano) e Palazzo Pitti (paredes com estalactites e estalagmites artificiais). Os Escravos permaneceram até 1908, quando foram transferidos para a Galleria dell'Accademia.
Of great repute are four statues in particular—known to scholars as "The Awakening Slave," "The Young Slave," "The Bearded Slave" and "The Atlas (or Bound)" because of their incomplete state. They are typical of Michelangelo's working technique called non-finito and, at the same time, stunning examples of conveying the idea of difficulties that beset an artist while extracting a figure from a block of marble, as well as mankind's aspiration to free a spirit from physical limitations.
There have been many different readings of these statues. One feels, at different stages in completion, the force with which creative ideas struggle toward liberty from the material weight and confinement surrounding them. They were possibly deliberately left incomplete by the artist to give expression to this universal condition whereby individuals strive to liberate themselves from their material constraints.
In viewing the Prisoners from several angles, Michelangelo’s deep feeling for and understanding of anatomy are revealed. While the heads and faces are among the least finished parts of these busts, they contribute very well to their basic meaning through their posture—classically in contrapposto. The Slaves place most of their weight on one foot so that this action causes the shoulders to slant against the hips and legs while, in turn, throwing one side of the body into marked disagreement with the other side. Movement is thus skillfully given to these carefully unbalanced figures as well as emotion; they also acquire a more dynamic, commanding presence as Prisoners due to this treatment by the artist.
The Accademia's unfinished sculptures by Michelangelo are an apt example clarifying his philosophy and technique of carving. According to him, a sculptor was only an instrument of God. Therefore, his role was not to create but to uncover the powerful forms within the marble. The material surrounding the figure is what Michelangelo needed to cut away. His work was merely cutting into the rock around those shapes so that they were brought out properly.
Vasari writes that he never took off his boots for days at a time, and used the same clothing while at work in order not only of efficiency but also of skill and experience since if one knows what he is about it is easy enough to keep clean white marble free from dust (and impracticably cold in winter).
Indeed, preliminary phases are distinguishable because remnants left by mallet and pointed chisel show clearly on marble surfaces from this period when shape began emerging; Michelangelo started back-to-front while working freestyle on figures unlike other sculptors who drew outlines on their blocks after making plaster models. Having no truck with plaster models (nor even drawing on paper), Michelangelo began right with raw marble—freely conceived in three dimensions all at once—attacking masses most heavily before going into details toward completion, always gaining anatomy progressively just as much as form overall so that every part reveals workmanship being executed freshly till last touch put down assuredly.
As Vasari described in his "Lives of the Artists," these figures appeared to stand up from the marble "as if a form were rising to the surface of water." His method was to put a wax figure into a vessel of water and then gradually to expose it, so that he might discern those parts which were projecting farthest. He worked in the same way, for himself extracting first those parts of highest relief.
In 1503, Michelangelo obtained a commission to make statues of the twelve Apostles for the Florence Cathedral. His work on only one piece, St. Matthew, however got started. He was called to Rome by Julius II soon after he began working on it, so that it became his first sculpture left unfinished.
After the contract for the twelve Apostles' statues was annulled on 18 December 1505, Michelangelo in all likelihood resumed his work on St. Matthew the following year. Several references in letters of that period and a stylistic feature typical of this phase allow us to make such a hypothesis: the torsion of the head of the saint in contrast to the position of the chest, which seems inspired by the Hellenistic group Laocoön and His Sons (unearthed in 1506) which Michelangelo came to appreciate during that same year.
The inscription on the base tells us how it was in 1831 that the statue was moved from the courtyard of the Opera del Duomo di Firenze to the placement in front of the Atrium of the Accademia di Belle Arti. Later, in 1909, it would shift next door to this gallery building, as did the Prisoners in that same year.