Vertical sundial on the south facade of the Second Secondary School. It was created by members of the astronomy section of the school (today Astronomical Society "Giordano Bruno") under the leadership of prof. Milan Stojanović. The azimuth of the sundial is 17° west, and the length of the shadow indicator is 26 cm. At the top is the inscription "Tempus fugit" (time flies). The sundial was set on June 8, 1999.

Ivica Marušić, a member of the astronomy section, in the description of the creation of the sundial in AstroBilten no. 3 says:
The culture of a society is reflected in the buildings it builds. Most often they are places of worship, pyramids, tombs, stadiums, squares, etc. Wanting to leave something beautiful behind us in this school, we decided to make a sundial to put on ours school.