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:

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
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
Higher septet of black squares in this grid, typographically
Writer who was the source of all the words with asterisked clues in this puzzle
Higher pair of black squares in this grid, typographically
This puzzle's theme found in the answers to five asterisked clues
Work by Sir Edward Elgar hinted at by this puzzle's circled squares
Locale for this puzzle's shaded squares
Movie good guys responsible for the circled squares in eight long puzzle answers
Fills, as black squares
Welcome mat spot (our puzzle title hints at the theme revealed by the pattern of circled squares)
Gather wealth by exploitation ... as hinted at by this puzzle's circled squares?
"Hmmmmm ..." [as hinted at by the three groups of black squares in the middle of the grid]
TREASURE HUNT STEP 2 (include black squares)
Dictionary source for each asterisked clue in this puzzle
What's revealed by connecting the special squares in this puzzle in order
Alice Walker novel ... or a hint to 12 squares in this puzzle
Type of gear on which the letters in this puzzle's nine theme squares are arrayed
What black and white squares do on a chessboard
Secret get-together, or what occurs literally in each of this puzzle's circled squares
What the answers to asterisked clues begin with