dreams or plans that are impossible or unrealistic
sueños o planes que son imposibles o poco realistas (suenos o planes que son imposibles o poco realistas)
"He’s always building castles in the air about his future."
"Él siempre está construyendo castles in the air sobre su futuro." (El siempre esta construyendo **castles in the air** sobre su futuro)
to agree with someone or have the same understanding
completely exhausted or tired due to overwork
to travel or walk around aimlessly
to address the audience directly in a play or film
at the very last moment
to blame someone else to save yourself.