What does "already" in “…so saturated with the past already” mean here?

Question

I always have problem with the meaning of "already". Oxford Dictionaries show it means:

1. Before or by now or the time in question.

1.1 As surprisingly soon or early as this.

2. North American informal
   Used after a word or phrase to express impatience.1

but I cannot understand which definition (or another one) fits with the phrase below:

It seemed the natural thing, to bring this voice from the past into a moment so saturated with the past already, even if the voice was mixed with my own.

The context is here:

For two days we explored Rome, a city that is both a living organism and a fossil. Bleached structures from antiquity lay like dried bones, embedded in pulsating cables and thrumming traffic, the arteries of modern life. We visited the Pantheon, the Roman Forum, the Sistine Chapel. My instinct was to worship, to venerate. That was how I felt toward the whole city: that it should be behind glass, adored from a distance, never touched, never altered. My companions moved through the city differently, aware of its significance but not subdued by it. They were not hushed by the Trevi Fountain; they were not silenced by the Colosseum. Instead, as we moved from one relic to the next, they debated philosophy—Hobbes and Descartes, Aquinas and Machiavelli. There was a kind of symbiosis in their relationship to these grand places: they gave life to the ancient architecture by making it the backdrop of their discourse, by refusing to worship at its altar as if it were a dead thing. [...]

The next morning was cloudless. We took a picnic of wine and pastries to the grounds of the Villa Borghese. The sun was hot, the pastries ambrosial. I could not remember ever feeling more present. Someone said something about Hobbes, and without thinking I recited a line from Mill. It seemed the natural thing, to bring this voice from the past into a moment so saturated with the past already, even if the voice was mixed with my own.

There was a pause while everyone checked to see who had spoken, then someone asked which text the line was from, and the conversation moved forward.
For the rest of the week, I experienced Rome as they did: as a place of history, but also as a place of life, of food and traffic and conflict and thunder. The city was no longer a museum; it was as vivid to me as Buck’s Peak.

Educated by Tara Westover

Answer 1

Which of the definitions is the right one -

Before or by now or the time in question.

Yes

As surprisingly soon or early as this.

No

Used after a word or phrase to express impatience

No

So, she is talking about "a moment saturated with the past". All their surroundings in Rome are imbued with historical context. It could be said they are "already" in the past, meaning that "before now", as in Definition #1, they have traveled back in a time machine. During the last one or two days, in fact. They have already gone back in time. Not at this very moment at the picnic. No. Rather, at a time before the present, which is referring to the entire stay in Rome.