In Romeo and Juliet Act III, Scene 3, what does "There is no world without Verona walls" mean?

In Act III, Scene 3 of Shakespeare's Romeo and Juliet, Romeo is hiding in Friar Lawrence's cell because of the tragic events in Scene 1 in which he killed Tybalt in revenge for the killing of Mercutio. When the friar informs Romeo that he has been banished from Verona for his part in the violence he immediately becomes passionate in his refusal to consider the decree. He has recently been married to Juliet and...

In Act III, Scene 3 of Shakespeare's Romeo and Juliet, Romeo is hiding in Friar Lawrence's cell because of the tragic events in Scene 1 in which he killed Tybalt in revenge for the killing of Mercutio. When the friar informs Romeo that he has been banished from Verona for his part in the violence he immediately becomes passionate in his refusal to consider the decree. He has recently been married to Juliet and claims that the outside world holds nothing for him if he cannot be with her. Furthermore, everything he knows and loves is in Verona. To be banished from the city is therefore worse than death. He cries to Friar Lawrence:

There is no world without Verona walls
But purgatory, torture, hell itself.
Hence “banishèd” is “banished from the world,”
And world’s exile is death.

Romeo refers to banishment as being like purgatory, a place in between life and the afterworld, torture or even hell. He carries on for quite a while about his fate in exile until the friar reminds him that he could have been put to death, as was the Prince's original declaration. Friar Lawrence eventually persuades Romeo to accept the law, go and see Juliet, and then leave for Mantua. He further encourages Romeo to look on the bright side of things and claims that once tempers have quieted Romeo may return to Verona and be reunited with Juliet:

Go, get thee to thy love, as was decreed.
Ascend her chamber. Hence and comfort her.
But look thou stay not till the watch be set,
For then thou canst not pass to Mantua,
Where thou shalt live till we can find a time
To blaze your marriage, reconcile your friends,
Beg pardon of the Prince, and call thee back
With twenty hundred thousand times more joy
Than thou went’st forth in lamentation.