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 Slavic name began to appear as "Papaldiv/n Plo(v)div, Pladiv, Pladin, Plapdiv, Plovdin", which evolved from a Thracian variant "Pulpudeva". As a result, the name has lost any meaning. In British English the Bulgarian variant "Plòvdiv" has become prevalent after World War I. The Crusaders mentioned the city as "Prineople", "Sinople" and "Phinepople". The Ottomans called the city "Filibe", a corruption of "Philip", in a document from 1448. Plovdiv is located on the banks of the Maritsa river, southeast of the Bulgarian capital Sofia. The city is in the southern part of the "Plain of Plovdiv", an alluvial plain that