An example of Irony in Macbeth

I like tha dramatic irony in Act 1 scene 6 is interesting. As King Duncan and Banquo near Macbeth's castle, Duncan thinks the air is gentle and sweet,

"This castle hath a pleasant seat; the air

Nimbly and sweetly recommends itself

Unto our gentle senses. "

Of course we already know that Macbeth and his wife are planning to kill him.