The exterior of the emplacement for one of two 6 inch BL (breech loading) disappearing guns emplaced at Lei Yue Mun Fort.  See <a href="//commons.wikimedia.org/wiki/File:6_inch_BL_Mk_IV_disappearing_gun_no._1_B_HKMCD.JPG" title="File:6 inch BL Mk IV disappearing gun no. 1 B HKMCD.JPG">Image:6 inch BL Mk IV disappearing gun no. 1 B HKMCD.JPG</a> for gun no. 1.  The Redoubt is to the left.  The fort now forms a large part of the Hong Kong Museum of Coastal Defence.
<a href="//commons.wikimedia.org/wiki/User:BrokenSphere" title="User:BrokenSphere">BrokenSphere</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>