Usage patterns
〈場所〉に見物人が集まるspectators gather at a place
A large crowd of spectators gathered at the fireworks display.
見物人でごった返すto be packed/crowded with spectators
The shopping street was packed with onlookers.
見物人を装うto pretend to be a bystander
The culprit stood at the scene pretending to be just a bystander.