Rummu quarry, <a href="https://en.wikipedia.org/wiki/Rummu" class="extiw" title="en:Rummu">Rummu</a>, Estonia. Limestone mining quarry was established in 1938. Limestone was mined by convicts of the adjacent Murru prison until the restoration of Estonian independence. The quarry filled up by natural water after mining was no longer necessary and draining of water was stopped. Abandonment of the quarry happened so fast that some machinery was sunken along with the building complex. The prison itself remained active until the end of 2012.
<a href="//commons.wikimedia.org/wiki/User:Iifar" title="User:Iifar">Ivar Leidus</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>