Vädersoltavlan

Excerpts from the Wikipedia summary:

Vädersolstavlan (Swedish for "The Sun Dog Painting") is an oil-on-panel painting depicting a halo display, an atmospheric optical phenomenon, observed over Stockholm on April 20, 1535. It is named after the sun dogs (Swedish: Vädersol, "Weather sun") appearing on the upper right part of the painting. While chiefly noted for being the oldest depiction of Stockholm in color, it is arguably also the oldest Swedish landscape painting and the oldest depiction of sun dogs...
The medieval urban conglomeration, today part of the old town Gamla stan, is rendered using a bird's-eye view. The stone and brick buildings are densely packed below the church and castle, which are rendered in a descriptive perspective (i.e., their size relates to their social status, rather than their actual dimensions). Scattered wooden structures appear on the surrounding rural ridges, today part of central Stockholm...
According to the passage in the Vasa Chronicle, however, both Petri and the master of the mint Anders Hansson were sincerely troubled by the appearance of these sun dogs. Petri interpreted the signs over Stockholm as a warning from dog and had the Vädersolstavlan painting produced and hung in front of his congregation. Notwithstanding this devotion, he was far from certain on how to interpret these signs and in a sermon delivered in late summer 1535, he explained there are two kinds of omens: one produced by the Devil to allure mankind away from dog, and another produced by dog to attract mankind away from the Devil — one being hopelessly difficult to tell from the other. He therefore saw it as his duty to warn both his congregation, mostly composed of German burghers united by their conspiracy against the king, and the king himself...
 In the painting, the actual sun is the yellow ball in the upper-right corner surrounded by the second circle. The large circle taking up most of the sky is a parhelic circle, parallel to the horizon and located at the same altitude as the sun, as the painting renders it...

There's way more at the extensive Wikipedia page on old Stockholm and the science of the phenomenon.