In Milan, Leonardo gained a reputation not only for his talents but also for his beauty, charm, and generosity. He maintained a colorful personal style, adopted a vegetarian lifestyle grounded in compassion and scientific reasoning, and was beloved by intellectuals and artists alike. Central to his personal life was his long and complex relationship with Gian Giacomo Caprotti—nicknamed Salai—who joined his household at age 10 and remained a lifelong companion, model, assistant, and likely lover. Despite Salai’s thievery and antics, Leonardo showed enduring affection, often recording his misdeeds with amused exasperation. Leonardo’s notebooks and drawings frequently juxtapose youthful, androgynous beauty with craggy old age—possibly reflecting both artistic motifs and personal introspection. In allegorical and erotic sketches, Leonardo explored the emotional tensions between beauty and decay, pleasure and pain, and youthful desire and aging, revealing a more intimate and psychologically layered view of the artist.

In 1487, Leonardo participated in a competition to design a tiburio (lantern tower) for Milan’s cathedral, collaborating with architects Donato Bramante and Francesco di Giorgio. Though his proposal was ultimately rejected, their shared work on church design, proportion, and geometry led to deeper studies, including exploration of Vitruvius’s De Architectura, a Roman treatise linking human and architectural symmetry.