First Church in Boston is a Unitarian Universalist Church (originally Congregationalist) founded in 1630 by John Winthrop's original Puritan settlement in Boston, Massachusetts. The current building is on 66 Marlborough Street in Boston. The church has long been associated with Harvard University.
The church was created in 1630 when the settlers on the Arbella arrived in what is now Charlestown, Massachusetts. John Wilson was the first minister, and the only minister while the church was in Charlestown. Two years later they constructed a meeting house across the Charles River near what is now State Street in Boston, and Wilson was officially installed as minister there. In 1633 John Cotton arrived from England, and was a teaching elder at the church, helping to establish the foundation of the Congregational Church, the official state church of Massachusetts. In 1677 Dorcas ye blackmore, a freed slave, was allowed to become the first African American member of the church.  In the 18th century, Charles Chauncy was a minister at First Church for sixty years and gained a reputation for opposing what he believed was emotionalism during the Great Awakening of Jonathan Edwards.
A schism developed at the turn of the 19th century, the trinitarian Christian church eventually transformed into a unitarian congregation by the mid-19th century along with many of the other state churches in Massachusetts. Massachusetts' state churches (largely Unitarian and Congregationalist) including First Church were officially disaffiliated with the government in 1833.
In the 19th century, the First Church moved to Back Bay in Boston. The building at 66 Marlborough Street in Boston dated from 1867 and was designed by Boston architects William Robert Ware and Henry Van Brunt. After a fire in 1968, First Church and Second Church merged and built a new building at the same location. This building, by architect Paul Rudolph, incorporates part of the facade of the 1867 building.
Second Church, founded in 1649 when the population spread to the North End legitimated an additional congregation sited closer to those individuals' homes, was also known as the "Church of the Mathers;" its pulpit was home to Increase Mather, Cotton Mather, and Samuel Mather from 1664 to 1741. Both churches were examples of the westward movement of Boston churches from the crowded, older downtown area to the newer, more fashionable Back Bay after it was filled in during the late 19th and early 20th centuries. Second Church's Back Bay location in the Fenway was sold (it is now owned by the Ruggles St. Baptist congregation) just before the merger.