If you're in the atrium of a building, you're in a large central space, often one that's open and airy. You might arrange to meet a friend in the museum's atrium because of its central location and open feel.
Often a key feature in a modern building, an atrium is usually spacious and several stories high with windows facing the sky. The atrium serves as a welcoming central area, with other rooms leading off of the space. An atrium can also refer to a chamber that's linked to other chambers or spaces. In your heart, the right atrium receives deoxygenated blood, while the left atrium receives oxygenated blood from the pulmonary vein.