Hong Kong’s M+ museum is facing additional delays as construction has fallen behind schedule again, the South China Morning Post reports.

The delay pushes the completion date back to late 2018, with the museum expected to open to the public in late 2019, two years later than originally planned.

Director Lars Nittve—who previously worked at the Tate Modern in London and Moderna Museet in Stockholm—admitted that M+ was the most challenging project he had been involved in.

“Conceptually it is quite groundbreaking, and it’s very complex and challenging,” he said. However, he insisted that despite the setback, once complete, the museum will transform Hong Kong’s cultural landscape.

According to Nittve, Alfred Pacquement, former director of the Centre Pompidou in Paris, called M+ “the most ambitious, complex and challenging museum project since the Centre Pompidou.”

A number of recent resignations have not helped in the development of the museum either. Michael Lynch, the chief executive of the West Kowloon Cultural District Authority—the organization behind the museum project—resigned in February and will leave his post in August.

The news was followed by another blow: senior curator Tobias Berger also resigned to become head of art at the Central Police Station art complex, also in Hong Kong.

Nittve agreed that Berger’s departure was a loss for M+ museum, but good news for Hong Kong’s art scene. “That’s part of our job—to grow the capacity for the arts in Hong Kong,” he explained.