The Royal Treasury Museum is a new addition to the Palácio Nacional da Ajuda in Lisbon, housing one of Portugal's most remarkable collections of royal jewels and decorative arts. A key challenge was making the public aware of this new space while honoring its close relationship with the palace. This thinking shaped the digital design: the museum's website and the palace's website were conceived as siblings — sharing a visual language and structural logic, yet each with its own distinct identity. Moving between the two sites, visitors can feel the connection while clearly recognizing where they are.