Trains, in a way, and the key to 18 of this puzzle's black squares. (Ones that begin with the keyword are asterisked. The others are for you to discover.)

Question:

Answer:

SHADOWBOXES

Length:

Similar Crossword Questions:

Complete set of 12 shapes formed by this puzzle's black squares
Web concerns ... and based on six familiar names hidden in rows 1, 4, 12 and 15 of this puzzle grid, what the black squares in those rows symbolize
On hold ... or what the seven rows of black squares in this puzzle's grid spell in Morse code
Row of black squares preceding or following six puzzle answers, thereby completing them
How this puzzle's black squares are arranged
Like aleph in the central black squares of this puzzle's grid
Term for each of the 15 asterisked theme answers in this puzzle
Number of times this puzzle's theme word appears diagonally in the grid (to complete the puzzle, shade those words plus the Down answers that begin where they meet)
What spouse does, step 4 [hint: look at the black squares of the grid]
Company "sorted" in this puzzle's circled squares
Angle irons graphically represented by four sets of black squares in this grid, and by letter formations starting in the four longest answers
This puzzle's theme, whose first notes are indicated by shaded squares
Your role in this puzzle [the asterisked clues will help you crack the case]
Visual representation of an item associated with the answers to the asterisked clues in this puzzle
Item with features that begin this puzzle's four longest answers
Octet of black squares in the middle of this grid, typographically
What the highlighted squares in this puzzle represent
The 2x2 black square near the middle of this puzzle's grid, e.g., which is part of eight answers
Nonet of black squares in this grid, typographically
How to unravel the answers to this puzzle's asterisked clues
Mail conveniences ... or a hint to eight squares in this puzzle
Company whose movies, not counting sequels, are all included in this puzzle [Circled Squares: 2009]
Landmark inaugurated 3/31/1889 whose shape is suggested by nine squares in this puzzle's completed grid
What's been deposited in four squares of this puzzle, expressed both by name and by symbol
Black Friday destination found in nine of this puzzle's Across answers