What do Lord Montague and Lord Capulet build in memory of their children and to mark the end of their feud in William Shakespeare's Romeo and Juliet?

Lord Montague promises to have a statue of Juliet built in pure gold; similarly, Lord Capulet vows to have one fashioned like Romeo. These statues will be a tribute of their love for one another.

In Act V, Scene 3, Prince Escalus of Verona calls upon Lord Montague to "see thy son and heir more early down" (5.3.223-224). Lord Montague reveals that his wife has just died in the night as the grief over Romeo's exile has overcome her spirit. Now he must be confronted with the death of his son. Then, as he sees Romeo's body, Lord Montague is overcome with his second loss. But, he soon learns that Paris and Juliet are also dead. Therefore, after shaking hands with Lord Capulet, he promises to have a statue constructed for Juliet,

...I will raise her statue in pure gold....
There shall no figure at such rate be set
As that of true and faithful Juliet. (5.3.315-317)

Hearing this, Lord Capulet then promises to have a likeness of Romeo constructed, also.

Furthermore, these statues will serve as eternal reminders of the tragedy of the young lovers who secretly wed and loved while the villainous violence of the feud between the Montagues and Capulets escalated around them. Indeed, this animosity between the two families is what caused the two youths to hide their love in the darkness