This past June, just as prime summer tourist season was about to kick in, the Museum of Modern Art, the city's third most popular museum with more than three million visitors a year, closed its doors for four months. The reason? A $450 million expansion, construction, and renovation project that not only increased the gallery space by 30% (and "other" public space by 25%), but also entailed a complete rethinking, reorganizing, and rehanging of MoMA's vaunted permanent collection. And now the job is done! This Sunday MoMA is open once again for a series of member previews, and on October 21st to everyone else. Here's a first look at the reboot.

That dramatically-lit canopy jutting out over the entrance on 53rd Street is new, but it's not until you enter the building that you notice how different everything is on the ground floor. The lobby itself is pretty much just a big empty space now, save for a new high tech coat room—there are no tickets; you enter your phone number on the touch screen and get a text with all the necessary info—which the staff says will speed up this most dreaded of all MoMA lines. To the east is a new Member's Desk, and the entrance to the beloved, unchanged Sculpture Garden.

To the west, there's a large new ticket-buying area, which now includes a bank of electronic kiosks, as well as a few spots to lounge about while overlooking the stylish new subterranean gift shop, which features a two-story "wall of books." Keep going and you'll discover the two new free-to-the-public galleries at the lobby level, called 1 North and 2 North, showcasing emerging artists. And no, that "Hello. Again." sign is not an Apple ad but, yes, everyone who visits will Instagram it.

On floors two, four, and five is where the increase in gallery space really hits you. The soaring Atrium is intact—Haegue Yang gets the space for the grand reopening—but basically everything else has expanded west, and you can tell you're entering new territory whenever you pass through a black-framed entranceway and/or see the name "David Geffen." There are an extraordinary number of (re)discoveries to be made on these floors, especially now that they've included many recent acquisitions by African, African-American, Asian, and Latin American artists, as well as more work by women artists in general.

The 2nd floor houses pieces from the 1970s to the Present, the 4th floor is all about the 1940s to the 1970s, and on the 5th, which covers the 1880s to the 1940s, is where you'll find the old crowd-pleasers like Monet's Water Lilies and van Gogh's Starry Night. I hadn't walked through these collection spaces in ages, and the juxtapositions between and influences among artists in these newly curated rooms were a revelation... and really fun to look at. If nothing else, the reconfiguration and re-theming of the galleries provide an excellent excuse to explore MoMA's riches with fresh eyes.

There are other new exhibition spaces throughout, including a performance "Studio" (on the 4th floor) that features a wall of windows and an engaging sound installation by David Tudor; and an Amy Sillman takeover (on the 5th floor) called The Shape of Shape, an "artist's choice" jumble of surprises and delights.

The 6th floor is the only one that doesn't flow through from old into new. The special exhibition galleries are still to the east (up the escalator), and that whole space is now taken up with a group show called Surrounds: 11 Installations, with rooms handed over to artists such as Sarah Sze, Rivane Neuenschwander, and Arthur Jafa. On the west side, accessible via a separate stairwell or elevator, is the new Terrace Cafe, notable for its outdoor tables.

There's a lot to be excited about here, but the question remains whether the expansion will ease the museum's notorious crowding.

The Museum of Modern Art is located at 11 East 53rd Street, between Fifth and Sixth Avenues, and will reopen for Member Previews on select days starting Sunday, October 13th, and to everyone, with regular hours, on October 21st. The price of admission remains $25 for adults.