how important are descriptions of places, architecture and clothes?

It depends if you care about making money.

Describe only the parts that the reader needs to form the rest in their head. Most of the novel will be imagined by the reader anyway so you just need to figure out what general ideas and concepts you want them to store. It gets pretty complex. But anyway if you dont care then dont put it in. Inflation wont help the writing

Post yer shit you overconfident sack a shit, he spat

>>8362393
Depends.
Take Lovecraft for example. He generally spent quite a bit of time (at least in his major tales) in describing places and architecture. Clothes on the other hand are very rarely described. In his style he favored accentuating elements that would be connected with horror and passing over whatever was irrelevant (hence the lack of character development as understood by audiences today, where the person has to have a generous amount of social links and must be thinking about and feeling 'normal people stuff' all the time).
I also agree with him that ideally this kind of description should serve a purpose in what's being written, but there are other authors who disagree and describe for its own sake. Others describe but not very extensively, to give some kind of grounding, especially about places. It all depends on what you want to do, but I think you can certainly write good stuff without putting those elements in if you think they're not necessary.

>>8362393
Yeah you should (Traditionally) be spending a paragraph on one single description. However its up to the author over what they want to describe; depends if you are you the author that describes the smile or the city.