The 360 deg. Brusio viaduct was built in the open as at this location it was not possible to build the loop in the mountainside. These loops are necessary to overcome the incline of the valley as without cogwheels the train cannot travel in a straight line.
<a href="//commons.wikimedia.org/wiki/User:GabrielleMerk" title="User:GabrielleMerk">GabrielleMerk</a>
<span class="int-own-work" lang="en">Own work</span>