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.