The 340-ton boulder journeying across Southern California crawled into Long Beach in the dark of night and parked on one of the city's busiest avenues, near some fast-food restaurants and a discount store.

The giant mass of granite will eventually be the focal point of artist Michael Heizer's "Levitated Mass" sculpture at the Los Angeles County Museum of Art. On its nine-day creep from a quarry in Glen Avon to Wilshire Boulevard it has been followed and photographed step by step.

Like many a weary traveler, it has stopped to rest during the day in a cross section of Southern California. A few days ago, it parked just off the 71 freeway in Chino Hills (where curious observers were asked to stay away because of the busy street) and over the weekened it stopped across the street from a regional park in Rowland Heights (where they were encouraged to bring a picnic.)

PHOTOS: Giant rock rolling toward LACMA

In Long Beach, the rock is now on Atlantic Avenue between 36th and 37th streets. Despite the fact that it blocks two lanes of traffic, locals planned a seven-hour welcome celebration.

"It's kind of an engineering marvel," said Long Beach Mayor Bob Foster, who greeted the boulder at 5 a.m. Wednesday. "It's a very large boulder, on a special platform, on a crane. And it's covered in what looks something like shrink wrap."

Interactive: Getting the rock ready to roll

The afternoon party, organized by city leaders and a local business association, starts at noon and promises a DJ playing songs with the word "rock" in the title, river rock decorating, photo ops with the rock and more.

RELATED:

Westward, ho! for LACMA's art rock

The LACMA rock: The overnight run to Long Beach

On the road with LACMA's big rock, minute by minute

-- Paloma Esquivel in Long Beach

Video: The rock moving overnight through Lakewood. Credit: County Supervisor Don Knabe