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 administrative structured units. According to the "Law for the territorial subdivision of the Capital municipality and the large cities," the territory of Plovdiv Municipality is subdivided into six district administrations with their mayors being appointed following approval by the Municipal Council. In 1969 the villages of Proslav and Komatevo were incorporated into the city. In 1987 the municipalities of Maritsa and Rodopi were separated from Plovdiv which remained their administrative center. In the last several years, the inhabitants from those villages had taken steps to rejoin the "urban" municipality. The city has more than 200 archaeological sites, 30 of which