Then (left): The home occupied by Justice Horace Gray. Gray was on the Supreme Court from 1882 to 1902. This structure later became the location of a Christian Science Reading Room.
Now (right): The Brutalist Third Church of Christ, Scientist. The church was built in 1971. Since opening, the building has not been well suited for the church, which has experienced declining attendance at its services. It currently has received the green light for demolition.
Thanks to reader Sean for the suggestion.