<a href="https://en.wikipedia.org/wiki/Horseshoe_Curve_(Pennsylvania)" class="extiw" title="w:Horseshoe Curve (Pennsylvania)">Horseshoe Curve</a>, Altoona, Pennsylvania, USA, 1954 centennial image in railroad museum
Unknown author<span style="display: none;">Unknown author</span>
Original item photographed by <a href="//commons.wikimedia.org/wiki/User:Brian_W._Schaller" title="User:Brian W. Schaller">Brian W. Schaller</a>