The line forms under the glass pyramid of the Louvre. It snakes up the escalator into the Richelieu wing, and up two more escalators to the second floor, and into the Salle Medicis. That is where Mona Lisa, also known as Lisa Gherardini, resides until October, when she will return to where she has spent the last 15 years, the Estates room, just off the Grande Galerie in the Denon wing.
You can say that it is the meeting of a work of Leonardo da Vinci and some of those of Peter Paul Rubens, as there are 24 paintings by the Flemish master in the Salle Medicis. Those were originally commissioned by Marie de Medici for her Luxembourg Palace, and they depict highlights of her life and, in particular, her marriage to King Henri IV of France, and how that marriage brought her to France.
Is it worth the one hour you will probably spend in the queue to find her in her new home? If your purpose is snapping a selfie and moving on, I can not say, as the point of that exercise escapes me altogether. But if you are interested in the art, I would say that it is truly worthwhile, and very much so. It is not every day that you have an opportunity to see the juxtaposition of works of two so very different masters of the Renaissance. The contrast between the austere modesty of the work of Leonardo and the sensual voluptuousness depicted by Peter Paul Rubens is fascinating. You can focus on the similarities and contrasts of these two masters of the Renaissance, one Italian and the other Flemish. Or you can remark how unlike each other they are in their perception and portrayal of femininity.
If you are not too tired from having queued so long, you can also take advantage of your presence on the second floor of the Richelieu wing to walk a few steps further, to the Rembrandt room. To reach it, exit the Salle Medicis through the portal opposite the entrance and turn left, traverse several rooms and descend the stair case to a mezzanine level and up the staircase on the other side of the landing, back to the second floor. Traverse several more rooms and turn left and continue another few rooms to number 845, the Rembrandt room. That trajectory, by the way, takes you through rooms filled with works of Antoine Van Dyck (former assistant of Rubens), various Dutch masters, a Vermeer (if it is back), two works of Frans Hals, and much more. So be prepared for serious distraction.
The Rembrandt room is perhaps my personal favorite part of the Louvre, particularly because of a number of self-portraits that depict him in various stages of his life. The earliest show a young man in his mid-twenties at the peak of prosperity and deeply fulfilled in a marriage of love with his wife, Saskia, who died some years later in child-birth. The latest, executed a few years before his death, depict the ruined wreck of an old man who seen it all and lost everything. The trajectory is breath-taking.