This is the "Apotheosis of the Medici" by Luca Giordano, painted in the Italian north. It's a preparatory work for the ceiling frescoes in the Palazzo Medici Riccardi, created between 1682 and '85.
The painting depicts the Medici family as embodying virtues. At the centre is Jupiter, surrounded by radiant light and supported by figures representing Glory and Wisdom. Below him, you'll see Cosimo I de' Medici, who became the first Grand Duke of Tuscany over a century ago.
At the bottom of this work, Apollo rides his chariot through the sky, accompanied by the Seasons. Above, the chariot of the Moon is drawn by bulls.
Giordano's use of mythology and symbolism here reinforces the Medici family's claim to virtue and their elevated status.
Apotheosis of the Medici hangs in The National Gallery on Trafalgar Square, London — free to enter. Point your phone at any artwork there and audioguide.london plays a free audio guide in six languages — no app download needed.