Where do the murderers go to kill Banquo in Macbeth?

Macbeth tells the murderers to kill Banquo at night in a park near the palace.

Macbeth comes to worry that Banquo knows that he killed Duncan in order to be king.  He also fears Banquo’s son, Fleance, because the witches told him that Banquo’s sons would be king.  Macbeth ponders what to do, and decides that Banquo is dangerous to him.

To be thus is nothing;But to be safely thus.--Our fears in BanquoStick...

Macbeth tells the murderers to kill Banquo at night in a park near the palace.

Macbeth comes to worry that Banquo knows that he killed Duncan in order to be king.  He also fears Banquo’s son, Fleance, because the witches told him that Banquo’s sons would be king.  Macbeth ponders what to do, and decides that Banquo is dangerous to him.

To be thus is nothing;
But to be safely thus.--Our fears in Banquo
Stick deep; and in his royalty of nature
Reigns that which would be fear'd: 'tis much he dares;
And, to that dauntless temper of his mind,
He hath a wisdom that doth guide his valour
To act in safety. (Act 3, Scene 1)

Naturally, Macbeth needs to have Banquo and Fleance killed.  To do the job right, he hires three murderers.  He tells them that Banquo is their enemy, and proceeds to explain to them where and how to kill Banquo and his son.

Within this hour at most
I will advise you where to plant yourselves;
Acquaint you with the perfect spy o' the time,
The moment on't; for't must be done to-night,
And something from the palace… (Act 3, Scene 1)

Macbeth chooses a park near the palace.  It is close enough that Banquo and Fleance can be waylaid on their way to the banquet, but far enough away that no one will hear them and raise the alarm.  It works beautifully, except that Fleance gets away.

Banquo makes it to the banquet after all, but he appears as a ghost.  Macbeth is so flustered by his appearance that his wife and Ross have to make excuses to the other guests and end the party early.  Macbeth’s reaction to Banquo’s death demonstrates that although he is ambitious, he still has moral reservations about what he is doing and will do.