Welcoming them on the red carpet was Latvian President Andris Berzins who said: "Tonight the leaders of the European Union and leaders of the Eastern Partnership countries will discuss the opportunities for future cooperation... the Eastern Partnership is not six months' activity during the Presidency. We started this activity many years ago and we see tonight as a basis for the future."
German Chancellor Angela Merkel, French President Francois Hollande and European Commission President Jean-Claude Juncker were all present, but with British Prime Minister David Cameron not due to arrive until Friday, his Foreign Secretary Philip Hammond deputised - and said Britain would attempt to address EU reform as well as the Eastern Partnership.
Latvian Prime Minister Laimdota Straujuma confirmed that while the leaders were enjoying some lavish Latvian hospitality, foreign Ministers would be closeted away in another building to thrash oout the text of the Riga Declaration to be released Friday.
On his way into the House of Blackheads where Berzins was playing host, President of the European Council Donald Tusk provided the best soundbite of the evening, saying:
"The Eastern Partnership is not a beauty contest between Russia and the EU, but let me be frank - beauty does count.
"If Russia was a bit softer, more charming, more atrractive perhaps it wouldn't have to compensate for its shortcomings by destructive, aggressive and bullying tactics against its neighbors," said Tusk.