The concrete blocks on the buildings to the left and center comprise part of the old sarcophagus built to contain radiation after the 1986 accident. This is as close as they'll take you, about 300 meters.
A new sarcophagus, an arch, is being built off to the right and behind this photo. It will slide on tracks right over the top of the old one. But radiation levels increase at higher elevations, making it unsafe to work at the top of the construction site, above thirty meters.
The really clever engineering solution: First they've built the top of the arch on the ground.
"We then attach some legs to that, which are the next part down. The
structure is then jacked 30m into the air, the legs swing in and are
tied together to prevent them from spreading out flat. We remove the
jacks, add another pair of legs, jack that up another 30m and the
process is repeated until we get the arch structure 110m up in the air," Dr. Eric Schmieman explains in this article.