Bulgaria's capital, Sofia is a capital city on a human scale with a population of 1.3 million. It is in the top 10 best places for business start-ups in the world and is one of Europe's most affordable cost-of-living capitals.
The National Palace of Culture (http://www.ndk.bg/) (abbrev. as NDK), in the heart of Sofia, is the largest multifunctional conference and exhibition centre in Southeastern Europe. It was opened in 1981 in celebration of Bulgaria's 1300th anniversary. NDK hosts over 300 events per year with 1 million guests. It is decorated with 80 monumental works of art implicated into the halls and foyers. It occupies an area of 123,000 m2 on eight floors and three underground levels.
Details about flights and public transportation can be found on CHEP2018.org.
Recommended hotels close to the venue can be found here: http://chep2018.org/lodging