Due to the nature of tabletop RPGs, a campaign will often start with a random group of strangers. Here are some ways to get them adventuring together, without resorting to the old Tavern trope.
The lengthy process to do something necessary or a magical scroll needed is inscribed on the other side of a great tapestry and can't be removed. For more fun it could be in the kings throne room. Try to hide in shadows with a 20*5 (yards/meters) monstrosity!