The flavourtext hints that all these puzzles are skyscraper puzzles. Ignoring the different coloured grid first, start by solving each of these skyscraper puzzles. Then, by either making an intuitive leap or taking a cue from the word “Front” written in each puzzle, we find out what each skyscraper puzzle layout will look like (assuming skyscrapers on white grids are white and those on red grids are red).

Each layout should clearly spell a letter, which collectively gives the answer VOUSSOIR, which is a wedge-shaped stone used to construct arches, linking back to the construction theme of this puzzle. Fun fact: In Visgothic architectural traditions, the voussoirs are often in alternating red and white – similar to our alternately coloured skyscrapers in this puzzle.