Little Tašmajdan is the eastern extension of the park, across Beogradska street which forms its western border, while Ilije Garašanina and Karnedžijeva streets form its northern and eastern borders, respectively. The southern section of the complex is the location of the Law Faculty and Hotel Metropol.
Cache is hidden in the area where the coordinates tell, but take care, there is cafe nearby so look out for curios muggles. Just sit on the benches and have a rest.
If you need aditional help, check out the hint!