you are likely to find Curtain in/at/on Theater. you are likely to find Person in/at/on Theater. 
Sight is a type of Position. Sight is a synonym of Spot. Spot is a synonym of Glimpse. 
Curtain --AtLocation--> Theater <--AtLocation-- Person 
Position <--IsA-- Sight <--Synonym--> Spot <--Synonym--> Glimpse 