Hire a top-tier gang of bricklayers, real masters at their art, and have them start building a circular wall around the Serpentine Gallery.
Around 3m high, this must be one of the finest brick walls ever built, equal to anything the Victorians did.
Once they’re close to completion, hire an unskilled gang to start demolishing the wall, using only hand tools. Have them remove every trace of it, including it’s foundations, it won’t be easy because it’s so well built.
Don’t stop employing either team, don’t change their instructions.