To grace in captive bonds his chariot wheels?

You blocks, you stones, you worse than senseless things!

O you hard hearts, you cruel men of Rome,

Knew you not Pompey? Many a time and oft

Have you climb'd up to walls and battlements,

To towers and windows, yea, to chimney-tops,

Your infants in your arms, and there have sat

The livelong day, with patient expectation,

To see great Pompey pass the streets of Rome:

And when you saw his chariot but appear,

Have you not made an universal shout,

That Tiber trembled underneath her banks

To hear the replication of your sounds

Made in her concave shores?

And do you now put on your best attire?

And do you now cull out a holiday?

And do you now strew flowers in his way,
That comes in triumph over Pompeys blood?
Be gone!
Run to your houses, fall upon your knees,
Pray to the gods to intermit the plague
That needs must light on this ingratitude."
(Act 1, scene 1, lines 33-56)
This passage is significant because it shows how all the Romans suddenly switched from Pompey to Caesar as their favorite.
It is also significant because it shows how Marullus doesn't want Caesar as king of Italy.

Context:
Marullus is furious because all the Romans are out in the streets celebrating Caesar. The Romans used to be loyal to Pompey, and now Caesar defeated Pompey so now he is some kind of hero? The Romans are taking the day of wearing their nicest clothes.