It remained within the borders of Bulgaria until July of the same year, when it became the capital of the autonomous Ottoman region of Eastern Rumelia.In 1885, Plovdiv and Eastern Rumelia joined Bulgaria.Numerous nations have left their traces on the twelve-metre-thick (39-foot) cultural layers of the city.The earliest signs of habitation on the territory of Plovdiv date as far back as the 6th millennium BCE.On September 5, 2014, Plovdiv was selected as the Bulgarian host of the European Capital of Culture 2019.This happened with the help of the Municipal Foundation "Plovdiv 2019″, a non-government organization, which was established in 2011 by Plovdiv's City Council whose main objectives were to develop and to prepare Plovdiv's bid book for European Capital of Culture in 2019.Although it was not the capital of the Province of Thrace, the city was the largest and most important centre in the province.The ancient ruins tell a story of a vibrant, growing city with numerous public buildings, shrines, baths, theatres, a stadium, and the only developed ancient water supply system in Bulgaria. In 179 CE, a second wall was built to encompass Trimontium which had already extended out of the Three hills into the valley.
The wettest months of the year are May and June, with an average precipitation of 66.2 mm (2.61 in), and the driest month is August, with an average precipitation of 31 mm (1.22 in).
Summer (mid May to late September) is hot, moderately dry, and sunny with a July and August having an average high of 33 °C (91 °F). The average depth of snow coverage is 2 to 4 cm (1 to 2 in), and the maximum is normally 6 to 13 cm (2 to 5 in), but some winters coverage can reach 70 cm (28 in) or more. The days are mild and relatively warm in mid spring.
Plovdiv sometimes experiences very hot days which are typical in the interior of the country. Autumn starts in late September; days are long and relatively warm in early autumn. The average January temperature is −0.4 °C (31 °F). The average relative humidity is 73% and is highest in December at 86% and lowest in August at 62%.
(39 sq mi), less than 0.1% of Bulgaria's total area.
It is the most densely populated city in Bulgaria, with 3,769 inhabitants per km². At the beginning of the 20th century, there were seven syenite hills, but one (Markovo tepe) was destroyed.