To begin with, Shakespeare starts Romeo and Juliet with the Prologue, which prepares the audience for the deaths of the two young lovers.
"Two households, both alike in dignity,
In fair Verona, where we lay our scene,
From ancient grudge break to new mutiny,
Where civil blood makes civil hands unclean.
From forth the fatal loins of these two foes
A pair of star-cross'd lovers take their life;"
(Prologue, Romeo & Juliet)
Then, in Act I, Scene I, there is a grand street fight which was bound to catch the attention of the groundlings who were standing in front of the stage in the Globe Theater. Even the Aristocrats, who sat on the upper benches that lined the circular shape of the Globe were caught up in the play through this introduction.
"Enter several persons of both houses, who join
the fray; then enter Citizens, with clubs and partisans.
Citizens. Clubs, bills, and partisans! strike!
beat them down!
Down with the Capulets! down with the Montagues!" (Act I, Scene I)