What types of details does Eliot use to recreate the market scene in Romola? Which details are specific to the novel’s time and place? Which details provide clues about daily life in fifteenth-century Florence?

Chapter 1 of George Eliot's novel Romola is set under the Loggia de’ Cerchi in a venerable Florentine neighborhood. At the chapter's inception, the character of Bratti Ferravecchi, a local shopkeeper, encounters a young man who has spent the night outdoors on the pavement. The young man is a stranger to Florence, and it is difficult for Ferravecchi to figure out his origins, as he wears an expensive jeweled ring but a shabby tunic and stockings. The situation of the characters—that of an experienced native and a stranger, respectively—is one of the devices used by Eliot to enhance her depiction of the market scene. As readers, we see the market through the dual perspective of someone who knows the scene well and someone who is unacquainted with it.
In addition to characterization and narrative perspective, Eliot uses other resources to create a richly historicized context leading up to and including the market scene. For example, he uses explicit historical references, such as that illustrating Dante's place of birth: "Qui Nacque Il Divino Poeta." He also uses dates—Eliot refers to the "9th of April 1492" and to the period of time in which the date falls ("the early decades of the fifteenth century, which was now near its end"). Direct references to dates are a rather obvious but nonetheless effective means of creating historical context.
Additionally, he uses allusions to contemporaneous events, such as the Frata Minori, a group that opposed the concessions allotted to Jews in the mid-fourtenth century:

Let me tell you the Frati Minori are trying to make Florence as hot as Spain for those dogs of hell that want to get all the profit of usury to themselves and leave none for Christians; and when you walk the Calimara with a piece of yellow cloth in your cap, it will spoil your beauty more than a sword-cut across that smooth olive cheek of yours.

He also employs references to then contemporary figures of social and literary importance, as in the following example:

the Medici and other powerful families of the popolani grassi, or commercial nobility, had their houses there, not perhaps finding their ears much offended by the loud roar of mingled dialects, or their eyes much shocked by the butchers’ stalls, which the old poet Antonio Pucci accounts a chief glory, or dignita, of a market that, in his esteem, eclipsed the markets of all the earth beside.

Eliot also uses narrative description: the following passage is typical of Eliot's exceptionally vivid, adjective- and adverb-laden prose style:

A vendor of old-clothes, in the act of hanging out a pair of long hose, had distractedly hung them round his neck in his eagerness to join the nearest group; an oratorical cheesemonger, with a piece of cheese in one hand and a knife in the other, was incautiously making notes of his emphatic pauses on that excellent specimen of marzolino; and elderly market-women, with their egg-baskets in a dangerously oblique position, contributed a wailing fugue of invocation.

Finally, Eliot uses dialogue within the market scene, as in the following example:

"And that reform is not far off, Niccolò," said the sallow, mild-faced man, seizing his opportunity like a missionary among the too light-minded heathens; "for a time of tribulation is coming, and the scourge is at hand . . . Florence will be purged."

Eliot combines all of these devices to create a scene that is at once engaging as a spectacle of local, pictorial interest and suggestive of historically-situated, dramatic narrative conflict.