The Smithsonian Castle and its surrounding museums are skipped altogether by many tourists visiting Washington, DC. But a reimagined layout for the Smithsonian Castle campus — said to be the most significant change to the National Mall in a century — seeks to change that. The new design, unveiled this week, plans to open up the campus around the Smithsonian's adminstrative building, which includes the Freer Gallery, the Hishhorn Museum, the (currently empty) Arts and Industries building, and the underground Sackler Gallery and African Art Museum.

The Smithsonian's cultural hub is located in the middle of the National Mall, between heavyweights like the US Capitol, the Washington Monument, the Lincoln Memorial, and the White House, which means it's got lots of competition. The current design, which is a mishmash of buildings built over the past century, can be difficult for tourists to navigate and isn't up-to-par for modern exhibitions. In addition, it faces away from the National Mall, making it less inviting to those walking from the US Capitol to other sites.

The primary issue fixed by the redesign is a pair of matching above-ground entrances to the Sackler Gallery and African Art Museum. The architectural team at the BIG-Bjarke Ingels Group has proposed peeling up the edges of the current Haupt Garden to make the new entrances and bring natural light to the galleries below. The portals, combined with a completely remade public square, should make an entirely new, inviting space.

The plan also calls for turning the Smithsonian Castle, dating from 1855, into the centerpiece of a visit to the grounds. The largely administrational building will be opened up inside, allowing for new spaces for services and other amenities. Making additional space from current buildings is central to the entire design — most of the structures would be modified under the plans to make additional space for galleries, bringing the exhibition spaces up to date for modern shows.

Unfortunately, you shouldn't expect to see any of these changes during your next visit to DC. The plans, which have been in the works for a year and a half, don't include a solid timeline or funding. The Smithsonian expects to use a mixture of public and private funding to raise the $2 billion needed for the project, and even then the renovations won't be complete for 15 to 20 years.