If you want to exchange everything we have for the coveted relics, we are ready to give it to you
(Princess Milica to Sultan Bayezid on the question of why she wants the "dry, immovable bones", Gregory Camblak, Letter on the transfer of the relics to the St. Petka's Monastery, 15th century )

It is believed that the original Chapel or Church of St. Petka was built in Donji grad of the Belgrade fortress, not long after 1404, when despot Stefan set up the capital of late medieval Serbia in Belgrade. The first church was built near a spring which was believed to have healing powers. Remains of old walls that were found by the builders of the new Chapel in the 1930s have confirmed the original location. The spring is mentioned by foreign travel writers such as Gerhard Cornelius Drisch in 1720, as a place where many peoples of different faiths gather.
The dome of the Chapel of St. Petka and a view of the confluence of the rivers Sava and Danube.

The new Chapel of St. Petka in the Belgrade Fortress was designed by the architect Momir Korunović and built between 1935 and 1937. It was preceded by a kind of primitive dugout decorated with icons, which was located above the spring. The interior of the Chapel, a simple, elegant cruciform building with a dome, has been decorated twice. For the first time in the classical fresco technique, by the academic painter Vladimir Predajević, professor at the Faculty of Applied Arts in Belgrade and copyist of Serbian frescoes at the Museum of Prince Pavle. It was decorated the second time with mosaics made by Đuro Radlović, also a professor at the Faculty of Applied Arts, in the period between 1975-1982.
The entrance hall of the Chapel of St. Petka and the mosaics by Djure Radlović that were created in the period between 1975 and 1982.

This is one of the most successful mosaic creations in contemporary Serbian sacral art. The meticulous technique, the vivid coloration dominated by a light blue color and gold accents, shows an interesting selection of subjects from secular and ecclesiastic history, in addition to the obligatory iconographic program of an Orthodox temple. Thus, on the walls of the Chapel, you can see Princess Milica, despot Stefan, Saint Sava and Saint Simeon, significant figures of Serbian medieval history, as well as an angel who with his touch transforms ordinary water into healing one - a motif that connects this spring and the biblical Pool of Bethesda.
A fresco of St. Petka and a wood-carved box with a part of her relics in the Chapel of St. Petka in Belgrade.

Even though the relics of Saint Petka have been moved from Belgrade a long time ago, except for a piece of them that is kept in a carved box under the saint's fresco, thousands of pilgrims still gather at the Chapel.