美国国会大厦圆形大厅（United States Capitol rotunda）是穹顶下方的中心大厅。据维基百科介绍，圆形大厅建于1818年至1824年，被誉为国会大厦的“象征和实体心脏”。

WASHINGTON, Jan. 20 (Xinhua) -- Donald Trump was sworn in as the 47th president of the United States in the Rotunda of the U.S. Capitol at noon on Monday, beginning his second term as he returns to ...