Tunnel construction of the <a href="https://en.wikipedia.org/wiki/Berlin_U-Bahn" class="extiw" title="en:Berlin U-Bahn">Berlin U-Bahn</a> between <a href="https://en.wikipedia.org/wiki/Kurf%C3%BCrstendamm_(Berlin_U-Bahn)" class="extiw" title="en:Kurfürstendamm (Berlin U-Bahn)">Kurfürstendamm</a> and <a href="https://en.wikipedia.org/wiki/Berlin_Zoologischer_Garten_railway_station" class="extiw" title="en:Berlin Zoologischer Garten railway station">Zoologischer Garten railway station</a>. The red line on a white background indicates that the stay between track and wall means danger to life.
The man-high recesses in the tunnel masonry serve as protection for railway workers.
<p><a href="//commons.wikimedia.org/wiki/User:Spielvogel" title="User:Spielvogel">Spielvogel</a>
</p>
<dl><dd>For a gallery of some more of my uploaded pictures see: <a href="//commons.wikimedia.org/wiki/User:Spielvogel" title="User:Spielvogel">here</a>.</dd></dl>
<span class="int-own-work" lang="en">Own work</span>