Gamzigrad-Romuliana, the imperial Palace of Galerius, is one of the most important Late Roman sites. It is located in in Gamzigrad, Serbia. Construction works started in 289 by the tetrarch Galerius to mark the place of his birth after a victory over the Persians. It was given the name Felix Romuliana in memory of his mother Queen Romula, a priestess of a pagan cult.

Like Diocletian's Palace in Split, the palace in Gamzigrad was designed to be a representative Imperial residence, housing the abdicated Emperor while retained the imperial symbols.

Archaeological excavations in the fortress revealed remains of a palace with exceptionally fine mosaics, baths and impressive gates. Among the important finds from the site are portraits of rulers made from the
Egyptian purple stone called porphyry and coins that help to date the complex.

Felix Romuliana is a UNESCO World Heritage Site. Among the reasons why it is a protected site is the fact that the complex is preserved in its integrity and authenticity up to now unlike many other buildings.  

​Sources:
https://www.worldheritagesite.org/
https://www.atlasobscura.com/
https://whc.unesco.org/

The Great Mosque in Pristina, Kosovo is an Ottoman mosque built in 1461 by Sultan Mehmet II Fatih. It was declared a Monument of Culture of Exceptional Importance in 1990.
 
The Mosque of Sultan Mehmet Fatih II is located in the old city of Pristina, near the Great Hammam (15th century), the Clock Tower (19th century), and the Academy of Sciences and Arts of Kosovo (19th century). The locals also call it "the Imperial Mosque".
 
Due to its structure and decorative elements it ranks among the most important buildings of Islamic architecture in Eastern Europe. It was built with carved yellow sandstones. The inside walls are lined with bricks joined and plastered with lime mortar. The building consists of a rectangular shaped space, a cupola, a minaret, and a representative porch. The dome of the Great Mosque is one of the largest domes of the 15th-century buildings in Eastern Europe.
Remarkable part of the interior is the wooden pew decorated with geometric ornaments. The inside walls are painted in various colours with plant motifs of the technique al Seko. In architectural, spatial, structural and decorative terms, the building retains all the features of its construction time.
 
It is a unique and dominating building on the landscape of Pristina. During the years, the Great Mosque has been restored several times, among which is worth mentioning the restoration of the years 1682-1683 (during the reign of Sulltan Mehmet IV), as well as the reparation interventions after the earthquake in 1955. 
 
Sources:
https://dtk.rks-gov.net/
https://en.wikipedia.org/