An interesting monument to see in Ljubljana, a symbol of the city, is the Robba Fountain (Fountain of the Three Carniolan Rivers). It's situated in Mesti trg Square in front of Ljubljana Town Hall, and is a good spot to enjoy nice views of the city's historic core and the people moving about here.
This Baroque fountain was completed in 1751 by Venetian-born sculptor Francesco Robba, who spent most of his life working in Ljubljana. The fountain he crafted is made of Carrara marble and consists of three male figures with water jugs, representing the three rivers of Carniola: the Ljubljanica, Sava and Krka. In it's center is a 10 foot tall obelisk made of local sandstone.
In 2006, the original fountain was renovated and moved into the National Gallery of Slovenia to protect it from future erosion (where you can visit it if so motivated). This fountain we see outside Town Hall today is a nice replica.