The One Campus Martius building was constructed in the late-modernist architectural style of the early 2000s, using glass, granite and limestone as its main materials. The lobby is home to a very unique structure: the world's largest indoor water feature. The water flows from the top of the atrium, passes through 15 vibrantly colored glass kites and flows into the lobby's water display. The display is surrounded by more than 3,400 square feet of open lobby space, allowing the flexibility to host events with up to 400 guests in a fully customizable layout. The OCM lobby leads to an extensive patio space that overlooks Campus Martius Park.