A dim-sum spot claiming to be the “largest Cantonese restaurant in the U.S.” has opened in Castro Valley.

HL Peninsula Restaurant held the grand opening for its newest location on Oct. 16 inside a former Rite Aid building. “With seating for up to 800 guests and nine private rooms, it’s an ideal venue for private parties, business events or intimate celebrations,” the restaurant says on its website, which also fetes it as the biggest of its kind nationwide.

HL Peninsula Restaurant now operates five locations across the region, including Burlingame, San Francisco and Milpitas. The San Francisco Chronicle was the first to report the news about Castro Valley.

While the claim about size has yet to be verified by Guinness World Records, HL Peninsula is definitely big: Its footprint covers more than 28,000 square feet, and its private VIP rooms include one that can seat 50 diners and other that has a table big enough for 30 — “a rare setup even in the Bay Area,” the restaurant says.

The restaurant is already taking advance reservations for weddings and other large events. There will also be dinner shows, if Yelp is to be believed, including one by an “internationally acclaimed magician and mentalist.”

The specialty at HL Peninsula is handmade dim sum, though there are plenty of other Cantonese specialties. The expansive menu covers everything from stir-fried lobster to wine-marinated oysters to roasted duck and pig’s feet to crab congee and paper-wrapped squab.

The location inside an old pharmacy has raised hopes for these forlorn ex-businesses on Reddit. “This is the second Rite Aid I know of that turned into a dim sum restaurant (also Grand Dynasty in San Jose),” wrote one user. “With the recent closure of all the Rite Aid locations I wonder if we’re going to see more of these pop up.”

Details: Open daily for lunch and dinner (with a break in between) at 3868 Castro Valley Blvd., Castro Valley; (510) 999-3838, hlpeninsula.com