The whole Huntington/Mass Ave area got shellacked on many sides the urban renewal club as part of either small-scale city plans, the Christian Science Center plans, and the Prudential Center plans - so I don't know what particular endeavor dropped that spaceship on Mass Ave. That particular building replaced a row of 4-5-6 story apartment buildings, most in the style of similar buildings still standing on Westland, Hemenway, and some of the streets in between. There actually used to be rows on
both sides of Mass Ave, but the east-side was also eliminated to open up a view of the Mother Church. These 4-7 story apartment buildings always once stood along both sides of Huntington and were similarly torn down for a motel and those ugly-as-shit concrete towers along Huntington.
Here's a photo of the area prior to full-scale renewal, you can a block that's already been cleared in the lower, far-left All of the streets west of Mass Ave used to continue across the street and continue to the east of Mass Ave - the coherent road network was another casualty of urban renewal.