The guy is guarding the entrance to the street (it starts between green and yellow buildings at the left), looks frozen but very attentive to the visitors. The view of the street and the clothes of the guardian refer to the times from the beginning of 20th century.
I decided to enclose the other photo for you, to get the full picture. Unfortunately this photo turned dark in my "professional" hands, so I had no courage to put it as a front page. But I am glad the soldier is not alone, he has a friend, the yard-cleaner (dvornik), who also is monitoring the street.
