In this poem, the speaker refers to a bunch of places where the ennui of modern life occurs. Basically, he is saying that the sorts of places in which people work and study and spend time in the modern world kind of sap their vitality and humanity.
The speaker lists a bunch of places where things like this occur. He talks about this happening in offices and in schools and in reception rooms specifically. He talks about switchboards and institutions. He even talks about lavatories, although those do not seem to fit the theme so much.
So, in general, the speaker is refering to places where we spend time and lose our humanity -- places that are generally like offices.
Although the poem is not specific about the institutions characterized by dolor, we may assume that Roethke is referring to places such as business offices, reception rooms, administrative offices, schools, and anywhere else where business is carried out and where files are kept. This makes sense with the diction that he uses concerning files, and whether he means a medical building or an office building, no one can truly be sure. All such places have in common a certain sameness and a certain banality of vitality and vivaciousness in which procedure takes precedence over life and spontaneity.