The Central European Bitcoin Expo (CEBE 2014) was held in Vienna, Austria. Vitalik Buterin attended and gave a presentation on Ethereum.

An interview with Vitalik at CEBE was compiled together with footage of Gavin Wood at Bitcoin2014 in Amsterdam:

The exact dates of the event require further verification — the issue description suggests May 16–18, 2014, while other sources indicate May 31 – June 1, 2014.