When do more than 200,000 square feet of newly minted office space, launched in the midst of a severely challenged market, go unnoticed?

When they’re inside a high-profile, 1,000-feet-tall mostly apartment skyscraper  on Fifth Avenue.

The Rabina-led project at 520 Fifth Ave., to be completed next year, is best known for offering 100 luxury condo homes. The KPF-designed tower at East 43d Street is hard to miss for its striking, double-height, terra cotta-framed arched windows.

But tucked inside will be 210,882 square feet of offices as well on 25 boutique-size lower floors, from the ninth through the 34th. They range in size from 6,500 to 12,000 square feet and are aimed at “tenants that want their own identities and sense of arrival when you get off the elevator,” said Benjamin Bass, the JLL executive managing director who’s leading the leasing campaign.

Despite the leasing market’s well-known challenges, Bass is confident that the new product will appeal to tenants in industries in addition to  the smaller financial firms that often seek modest footprints. Proximity to  Bryant Park and Grand Central Terminal are powerful draws, he said.

What’s more, most office floors come with much in demand terrace or loggia outdoor space. Tenants will have access to a large-scale amenities center for which details aren’t yet available.

“The supply of trophy-quality space in Midtown has diminished,” Bass  said. “There’s been a tightening effect. We’re well-positioned” to exploit the situation.

Rabina took over the long-stalled project from Ceruzzi Properties and SMI USA in 2019. It nailed down a $540 million construction loan package in early 2022.