Just like many other big cities in the US, downtown Boston definitely has brutalist areas, probably due to being built back when brutalism was a common style -- for example, Boston city hall is in brutalist style [1]. However, the most common architectural style in Boston is red-brick. Even some modern high-risers are built to look in this style.

[1] https://en.wikipedia.org/wiki/Boston_City_Hall#/media/File:B...