Dude, I’ve never remotely even heard of “Secret Of Monkey Island”!
Now, Colossal Cave, a.ka. Adventure, is a very strong contender, particularly as it is famous for that immortal line, You are in a maze of twisty little passages, all alike.
Nonetheless, I think the most famous text adventure game of all time, would have to be Zork I, with its iconic starting location, West of House. 