I never know why you are at a loss.Attend has a preposition (to) as (phr v);so when you say attend never takes preposititon is wrong.At last not least we can say that more than twice Place with (where) refers to the purpose of it, but place with (which )refers to the discription of it . What I want to say for all;don't hustel after the idol rule of which or where ; your answer key with (attend). please everybody ,try to cosult the dictionary to know the meaning of attend with place.Best wishes for all .MR.HATEM ATTIA