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 Airport and Frankfurt) in 2015 after two years of stable operation. The government have started the first concession procedure back in 2011, but there were no candidates for it. The second attempt for the concession was made in the spring of 2016 when the government have opened a tender for a 35 years concession of the airport, but the tender was shortly cancelled for non-compliance with European rules. In December 2016 the government opened the 3-rd tender for the concession. In the new procedure 3 companies have made the bid for the airport - Silk Road Plovdiv Airport, Consortium Plovdiv Airport