PROSPECT HEIGHTS — The brand new Barclays Center boasts innovative architecture, fancy suites and a unique herringbone basketball court, but it's lacking one humble necessity — toilet paper.

Department of Health inspectors this month hit the freshly opened arena's Calvin Klein Courtside Club with four violation points after they discovered the bathroom at the exclusive lounge was "not maintained and provided with toilet paper, waste receptacle and self-closing door."

The club is one of several premium venues at the arena. It's positioned right outside the Brooklyn Nets locker room and is described on the arena's website as "a new standard of luxury."

The Courtside Club is among nearly 40 restaurants and concessionaires at the Barclays Center that have already been subjected to a round of inspections by the Department of Health, which issues the city's restaurant grades.

None of the restaurants or vendors at Barclays Center have received final grades yet from the Department of Health, but some were issued violations during initial inspections, carried out in some cases before the arena opened on Sept. 28.

A few concessionaires got slapped with "critical" violations that could result in poor letter grades if not corrected. The Honda Club, another premium lounge area, received 12 violation points because inspectors found flies, and because the facility wasn't "vermin-proof" during an Oct. 2 inspection.

The club was also missing a "wash hands" sign at its "handwashing facility."

A "wash hands" sign was also absent at the 40/40 Club, the arena's branch of Jay-Z's Manhattan nightclub, where inspectors issued two violation points during an Oct. 2 inspection — the same week the hip-hop mogul was breaking in the new venue with a series of sold-out concerts.

Inspectors also failed to find "wash hands" signs at the MGM Foxwoods Bar, the L&B Spumoni Gardens and Beer Room, and at the South Suite Stoli Bar.

The Robert Mondavi Winery was issued 13 violation points for having flies, for not being "vermin-proof," and for having an improperly constructed "non-food contact surface" during a Sept. 10 inspection, before the arena opened.

Barclays Center spokesman Barry Baum said the inspections were "pre-permitting inspections to determine if the construction, including installation of signage and sealed holes to prevent vermin, was complete."

He noted that all 50 of the arena food vendors subject to Department of Health review passed inspection and will be issued permits. "We are not yet two weeks old and are working to ensure we meet the highest standards," Baum said in an email.

New York restaurant owners have criticized the city's health grading system as inconsistent and arbitrary, but the city has credited it with making restaurants safer and cutting down on salmonella outbreaks at eateries.