Insert four letters, which represent a place, to create what may be seen in that place.
N E T
N E T
I think the letters to insert are
MOMA, as in Museum of Modern Art. The words then become MONET and MANET, whose paintings would be showcased in such a museum. The title also confirms this, as both Monet and Manet were Impressionists.
I don't think this is what you mean, but
If i add the place "WORK" then I may see a NETWORK at WORK
First impressions count at work (interviews)
It doesn't explain the two NETs nor the visual tag