Image by Mladen Savkovic Lonely Planet
This splendid brick tower (1896) has been renovated to house a free gallery, which hosts regular exhibitions. The views from the top, especially at sunset, are breathtaking. Somewhat confusingly, it's also known as the Millennium Tower.
From Zemun's buzzy Sinđelićeva, the tower is a five-minute walk up the cobbled street of Grobljanska.