Plovdiv reached an agreement that the Principality of Bulgaria and Eastern Rumelia had a common government, Parliament, administration, and army. Today 6 September is celebrated as the Unification Day and the Day of Plovdiv. After the unification, Plovdiv remained the second most populous city in Bulgaria after the capital Sofia. The first railway in the city was built in 1874 connecting it with the Ottoman capital, and in 1888, it was linked with Sofia. In 1892 Plovdiv became host of the First Bulgarian Fair with international participation which was succeeded by the International Fair Plovdiv. After the liberation, the first brewery
Plovdiv the year. Mists are common in the cooler months, especially along the banks of the Maritsa. On average there are 33 days with mist during the year. The history of Plovdiv spans more than eight millennia. Numerous nations have left their traces on the cultural layers of the city. The earliest signs of habitation on the territory of Plovdiv date as far back as the 6th millennium BCE. Plovdiv has settlement traces including necropolises dating from the Neolithic era, roughly 6000–5000 BCE, like the mounds Yasa Tepe 1 in Philipovo district and Yasa Tepe 2 in Lauta park. Archaeologists have