MADRID — On a warm spring day outside Estadio Vicente Calderón, home of Atlético Madrid, a couple of workmen in fluorescent yellow vests are attending to a large steel door. One has the easier job, languorously holding the door in place as his colleague strains to tighten a dozen studded bolts in turn. After a few minutes of grunting and heaving, the two men swing it open and shut, open and shut, to test that it is firmly fastened.

It feels fitting, somehow, that just a few weeks before that door closes for good — along with all of the others in this peeling, patchwork concrete bowl a gentle 15-minute walk south of downtown — there is still work to be done. The Calderón has always had the air of a place that would be wonderful, if only they could finish it.

Time, though, has run out. The Calderón has long looked as if it is on its last legs; now it actually is. The next three weeks or so will act as one long goodbye, as this stadium, one of the most intimidating in European soccer, ticks off the milestones on its road to ruin.

On Wednesday, the Calderón will host its final European game, the second leg of Atlético’s Champions League semifinal against Real Madrid. For a club that has long nursed an inferiority complex to its wealthier, more glamorous neighbor, the game is the perfect send-off: Real Madrid won the first leg, 3-0, ensuring that what should have been an evening of noise and passion and hope will almost certainly end in disappointment.