Romeo and Juliet is a tragedy written by William Shakespeare early in his career about two young star-crossed lovers whose deaths ultimately reconcile their battling families. It was among Shakespeare's most popular plays during his lifetime and along with Hamlet, is one of his most frequently performed plays. Today, the title characters are regarded as archetypal young lovers. They are considered the perfect model for the young love.
Romeo and Juliet belongs to a tradition of tragic romances stretching back to antiquity. Shakespeare's use of his poetic dramatic structure has been praised as an early sign of his dramatic skill. The play assigns different poetic forms to different characters, sometimes changing the form as the character develops. Romeo, for example, grows more proficient at the sonnet over the course of the play.
The play is set in Verona, Italy, begins with a street fight between Montague and Capulet servants who, like their masters, are sworn enemies. Prince Escalus of Verona mediates and declares that further rupture of the peace will be punishable by death. Later, Count Paris talks to Capulet about marrying his daughter Juliet, but Capulet asks Paris to wait another two years and invites him to attend a planned Capulet ball. Lady Capulet and Juliet's nurse try to persuade Juliet to accept Paris's courtship. But contrary to everyone’s wishes and better fate Juliet fall in love with one of the Montagues, Romeo, and the tragedy properly starts.
From the options you presented in the comments the best line that best reveal the dramatic irony is :
The last line.
O, well-a-day, that ever I was born!
Some ae, h! My lord! my lady!