Diocletian was known as a great reformer of the Roman Empire because he introduced a system called tetrarchy, which is simultaneously governed by four rulers. He was a persecutor of Christians who were considered gods. The great palace in the area of today’s Split was built to spend pension days in it. Diocletian’s Palace is the largest and best preserved late antique palace in the world. The east and west walls are 216 m long, 181 m south and 175 m in the north. In the northern part of the palace there was room for servility and army while the south were the carve chambers themselves. In use, it was a water supply that supplies water from the source of the Jadro River and is used in one part today.