In 1783 and 1784 it served as the capitol building of the United States Congress of the Confederation, and is where Ratification Day, the formal end of the American Revolutionary War, occurred.

The two-story brick Georgian style structure, located inside State Circle, was designed by architect Joseph Horatio Anderson.

A small portico juts out from the center of the building, topped by a pediment, with two high arched windows framing the entrance.

A cornice is topped by another pediment and the sloping roof gives way for a central octagonal drum atop which rests a dome.

The large dome is topped by a balustraded balcony, another octagonal drum and a lantern capped by a lightning rod.

The current state House of Delegates and Senate chambers are part of the annex, which is clad in black and gold Italian marble.

[8] Adjacent to the State House is Lawyers Mall, an open space which was designated in 1973 after the demolition of the Court of Appeals building, which had sat at the location since 1906.

Statues of Baltimore native Thurgood Marshall, the first black U.S. Supreme Court justice, as well as Donald Gaines Murray, the first African-American to enter the University of Maryland School of Law since 1890, and a bench with statues of two anonymous children symbolizing the victory of Marshall's litigation in Brown v. Board of Education, all sit on Lawyers Mall.

[13] In the wake of the Charlottesville car attack in 2017, House Speaker Michael E. Busch called for the removal of the Taney statue,[14] as did Governor Larry Hogan a day later.

It was again put on display in March 2020 alongside the original Star-Spangled Banner by Francis Scott Key on loan from the Maryland Center for History and Culture.

[19] Above the fireplace is the painting Washington, Lafayette & Tilghman at Yorktown by Charles Willson Peale; the work was commissioned by the Maryland Legislature in 1783 and added to the State House collection the following year.

[20] On February 2, 1781, Governor Thomas Sim Lee signed and sealed the "act to empower the delegates of this state in Congress to subscribe and ratify the Articles of Confederation.

"[22] The decision established the requisite unanimous consent of all thirteen states for the formation of a Perpetual Union.

Two famous Marylanders are featured in statues flanking the podium: John Hanson, the first president by the Articles of Confederation, and Charles Carroll, one of the signers of the Declaration of Independence.

Four portraits of Declaration of Independence signatories for Maryland hang on the walls: William Paca, Thomas Stone, Samuel Chase, and Charles Carroll.

[28] The Caucus Room houses most of the 48-piece silver service from the armored cruiser USS Maryland, which was decommissioned in 1947.

Portraits in the room are originals depicting Oden Bowie (by Katherine Walton),[32] Frank Brown (by Louis P. Dieterich),[33] Leonard Calvert (attributed to Jacob van Oost or Jacob van Oost the Younger),[34] Elihu Emory Jackson (by Ida Foster),[35] Robert M. McLane (by George Peter Alexander Healy),[36] Thomas Swann (by Florence Mackubin),[37] Francis Thomas (by Franklin Barber Clark),[38] William Pinkney Whyte (by David Bendann),[39] and Levin Winder (by Florence Mackubin).

[40] The room also contains reproductions of portraits of Clarence W. Blount (by Simmie Knox)[41] and Mary Eliza Watters Risteau (by Talmadge of New York).

It was in the Old Senate Chamber that Congress ratified the Treaty of Paris on January 14, 1784, formally ending the American Revolutionary War.