2. Podrumi, Split

Nestled in the heart of the ancient city of Split, Croatia, the Podrumi, or the Cellars of Diocletian's Palace, offer a remarkable glimpse into the past. These subterranean chambers are a testament to the grandeur and complexity of Roman architecture and engineering. Built between the late 3rd and the early 4th centuries AD as part of the retirement residence for Emperor Diocletian, the cellars represent one of the best-preserved ancient complexes of their kind.

The sprawling network of rooms and corridors beneath the palace was meticulously designed to support the structure above while providing storage and possibly serving as servants' quarters. Visitors to the Podrumi can wander through the vaulted halls that once housed supplies such as wine, oil, and food, necessary to sustain the imperial court. The cellars' symmetry and alignment with the upper residential floors showcase the precision of Roman planning.

Today, the Podrumi are not only a historical site but also a cultural venue. They have been transformed into a bustling hub with shops, galleries, and seasonal events, allowing tourists and locals alike to engage with the city's heritage in a lively and interactive setting. The atmospheric passageways also serve as a popular filming location, most notably featured in the television series "Game of Thrones."