Abstract: An apparatus includes an arch-support system configured to support an archway above a work surface during construction of the archway. A rail assembly is configured to selectively receive and support the arch-support system in such a way that the rail assembly, in use, supports the arch-support system once the rail assembly selectively receives the arch-support system.

Abstract: An apparatus includes a monolithic retaining wall formed by combinable modular retaining wall blocks. Each of the combinable modular retaining wall blocks defines (A) vertical grooves extending along a vertical direction, and (B) horizontal grooves extending along a horizontal direction. This is done in such a way that the monolithic retaining wall, which is formed by the combinable modular retaining wall blocks, defines (A) spaced-apart instances of the vertical channels extending vertically through the monolithic retaining wall, and (B) spaced-apart instances of the horizontal channels extending horizontally through the monolithic retaining wall, in which at least some of the spaced-apart instances of the horizontal channels intersect at least some of the spaced-apart instances of the vertical channels.