The Portland Art Museum has announced that it has agreed to an art-loaning partnership with members of Mark Rothko’s family, which will allow the institution to exhibit major paintings from the Rothkos’ private collection over the course of the next two decades.

“Our family is thrilled to enter into this partnership with the museum,” Christopher Rothko said. “Portland played a formative role in my father’s youth, and we are eager to share these works with the public and give Rothko a more active role in the vibrant cultural life of this city.” Christopher Rothko and Kate Rothko Prizel, the Abstract Expressionist’s children, will be loaning the works.

The museum is also planning an expansion project, including a new glass-walled building that will add 30,000 square feet of space. At the request of the anonymous lead donor, it will be named the Rothko Pavilion in honor of the artist’s legacy. Born as Markus Yakovlevich Rotkovich in Latvia in 1903, Rothko settled with his family in Portland when he was ten years old. His first solo exhibition was organized by the Portland Art Museum.

Designed by Chicago-based Vinci Hamp Architects, the three-story pavilion will be connected to the main building and will feature 9,840 square feet of exhibition space, a third-floor sculpture garden, a new education and design lab, and additional space for the museum’s library.

Slated to open between 2020 and 2021, the expansion will cost approximately $75 million, which includes the cost of construction and establishing an endowment. To date, the museum has raised $21.75 million.