This structure is an artificial object made of brick pavers and (?) wrought iron and is automatically an immovable obstruction under the Definitions in the Rules of Golf. It could be declared by the Committee to be an integral part of the course, which would be unreasonable and unjust considering the proximity of the open drain – which is an integral part of the course.
Free relief from an immovable obstruction is only available if it interferes with your stance or swing. Intervention on your “line of play” is not interference. However, if you were unlucky enough to be in the race track and the “winning posts” were on your line of play you could obtain free relief by exercising your rights, under the local rule pertaining to the danger of hitting the running track railing, which is also alongside the “winning posts” within the race track. In exercising your rights, you could go back as far as you like, keeping the race track rail and the flag in a straight line and take free relief.