"Look! Take photos!"
-- Henry Shaw to his son Langdon outside the City Hall subway station (WFT)
A Magical Barrier Energy Field in the form of a protective bubble was placed around the entrance to City Hall subway station in 1926 New York in order to trap Obscurial Credence Barebone (WFT).
It is also referred to as a “magical force field,” which appeared as a “luminous wall of vibrating energy” (WFT).
References from the canon
As Newt Scamander dueled on the subway tracks with Gellert Grindelwald in disguise as Auror Percival Graves, Credence in his Obscurus form began to destroy the station with his Dark energy. The Magical Barrier began to break down around the entrance and the spectators had to flee (WFT).