For those lucky enough to take part in Saturday’s Cambridge Community Day at the renovated Harvard Art Museums – and even for those who have to wait a whole other day until the museums’ formal opening – there’s a lot to appreciate about the new, combined facility.

The collections from the Fogg, Busch-Reisinger and Arthur M. Sackler museums look refreshed in the $350 million, 204,000-square-foot building by Pritzker Prize-winning architect Renzo Piano. The brightness of the building, whether it’s from a fresh coat of paint or five-story, Italian piazza-style Calderwood Courtyard, makes every piece look like a revelation. Merely being seen after six years of construction probably also has something do with it, although there is also 40 percent more gallery space and plenty of new items, with officials saying the pace of donations accelerated as people realized the museums’ reopening was increasingly near.

Cambridge Community Day takes place from 10 a.m. to 7 p.m. Saturday. While the special opening celebration is sold out, as of Sunday the museum website was still taking a few reservations for Tuesday time slots. Whenever you get to visit the new 32 Quincy St. combined structure – and remember that the museums are free on any day for Cantabrigians with proof of residency – here are some things to look for, or forward to:

The Calderwood Courtyard. This one is really more of a “look forward to,” since you don’t need to “look for” the courtyard. Harvard calls it the “historic heart of the original Fogg Museum,” and it’s both where you enter the museums (from either Quincy Street or the Prescott Street ramp) and where you want to linger. The new glass roof allows controlled natural light into the heart of the building, and it’s a handsome, soaring and peaceful place. It’s also open to the public without paid admission to the galleries – it’s where you get access to the ticket booth, gift shop, café and all three museums, so you can choose whether to head to the galleries of the original Fogg (Western art from the Middle Ages to the present) or relocated Busch-Reisinger (works from central and northern Europe, mainly from German-speaking countries) and Arthur M. Sackler (Asian art) … or just hang out.

Small galleries that are the next best thing to being outdoors with art. The ground-level floor and the story above each have great small galleries with floor-to-ceiling views – either of Broadway and its cozily academic-looking brick apartments, or of the neighboring Harvard Film Archive, which itself just looks like a giant, outdoor sculpture. Docents say these nooks, with their natural light and slight remove from the main structure, are already popular, even (or especially) at dusk and in the dark.

The relocated fresco. Harvard grad Lewis Rubenstein and his mentor, Rico Lebrun, painted this “Hunger March” fresco on the Fogg’s fourth floor in 1933 (for a building that had just opened in 1927), combining Renaissance-era techniques with incidents ripped from the day’s headlines and dramatizing the era’s social movements. The renovation compelled the moving of the fresco, which modern and contemporary art curator Sarah Kianovsky called a huge technical challenge. Look above the fresco – which itself is high on the wall, representing its height where Rubenstein and Lebrun painted it – and you’ll see that plenty of the fourth-floor ceiling came with it. “It was the only way to be certain the fresco wouldn’t crumble,” Kianovsky said.

The Lightbox Gallery. Atop the museums, and providing a stellar view not just down to the courtyard but into the restoration and curatorial work of staff and students, is a technological treasure unique to Harvard: a giant screen able to display and sort every item on display in the galleries – which is, incredibly, only 1 percent of the entire 250,000-item collection, according to lonely Lightbox Gallery attendant Christopher Molinski, a Robb curatorial fellow for academic and public programs. First came the excellent real estate. “We thought, ‘What kind of technology should be in this space?’” Molinski said, describing a yearlong process by the school’s metaLAB that played off of ideas in its existing Curarium “animated archive.” “You can quickly see every object on display and re-sort from any piece of data,” Molinski said, allowing visitors to “see how objects relate to each other” even when they seem nothing alike.

Docents upon request. The completion of the museums means that the art restorers and experts working in Somerville during renovations have come home. Their return in October doesn’t mean just new workspace to toil in on the airy upper floors, but a little-known resource for visitors who give museum managers plenty of warning: Decide which objects matter the most to you and you can request a docent to come down and give you the Harvard expert-level run-down on that object or era, said Stephanie Rozman, a Calderwood curatorial fellow for Asian and Mediterranean art.

Bonus: The Mark Rothko murals, before and after. One of the museums’ opening exhibits brings back Mark Rothko murals displayed in the Holyoke Center in 1964 – and restores them to looking as they did at the time, despite the damaging effects of time and environment. Since trying to essentially re-paint the Rothkos would destroy the unique stroke that makes the paintings live, said Carol Mancusi-Ungaro, of the museums’ Center for the Technical Study of Modern Art, restorers had to find a different way to color correct. They worked on the problem for 13 years, deciding six years ago on an innovative approach that brought in fellow experts from as near as the Massachusetts Institute of Technology and as far as the Digital Humanities Lab at the University of Basel, Switzerland. The solution: digital projectors with 2 million pixels painstakingly customized to shine specific hues at different portions of paintings to account for subtly differing degrees of degradation.

There are many virtues to the exhibit, including sketches for paintings that show the artist’s process and never-before-seen panels that Rothko arrived in 1964 with but ultimately rejected as part of his display. But the prize is that the digital projectors are turned off a 4 p.m. daily, meaning if you’re in the gallery at 3:59 p.m. you get to see the stark difference between the color-corrected Rothkos and their unlit reality. Keep an eye on Panel 5 – it’s the most dramatic correction – and prepare to be impressed by the team’s solution.