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 in Silistra Eyalet between 1593 and 1826, the sanjak centre in Eyalet of Adrianople between 1826 and1867 and the sanjak centre of Edirne Vilayet between 1867 and 1878. During that period Plovdiv was a major economic center along with Constantinople, Edirne, and Thessaloniki. The richer citizens constructed beautiful houses many of which can still be seen in the Architectural reserve Old Plovdiv. Under the rule of the Ottoman Empire, Filibe (as the city was known at that time) was a focal point for the Bulgarian national movement and survived as one of the major cultural centers for Bulgarian culture and