Somewhere Under the Rainbow?

Nope, Judy Garland was wrong.

As it turns out, Damon Runyon gave me the clue I needed in his song
My Time of Day.

You remember the song from
Guys and Dolls, right?

…When the street belongs to the cop
And the janitor with the mop
And the grocery clerks are all gone.
When the smell of the rain-washed pavement comes up clean, and fresh, and cold, and the street lamp fills the gutter with gold.

The key to finding the gold was to look under the street lamps at exactly 4AM. But you've got to take a leprechaun with you. This is Alf.
I promised him 20 percent.