The bloc's poorest but most euro-optimistic member state completed a costly refurbishment of its National Palace of Culture, built in 1981 during the country's communist era, to host meetings of the six-month revolving presidency.
The capital's airport was also made easier to access by the hasty completion this week of a new fast road linking it to the boulevard leading downtown.
Electric cars were hired to drive the EU delegates around, in a move to show Bulgaria's commitment to preserving the environment.
But Sofia remains one of Europe's most polluted capitals due to its extremely poor air quality -- a problem that unlike pot-holed roads is impossible to hide.
As is does every winter, thick smog blanketed the capital, with wood and coal burnt for heating and the use of outdated vehicles widespread.
The concentration of fine particles in Sofia's air on Wednesday was up to four times the recommended limit, according to data from the executive environment agency.
In an attempt to improve the situation, Sofia's municipal authorities ordered the main boulevards to be washed and installed special gas analysers in its main police vehicle inspection checkpoint.
Recent data showed that 43 per cent of cars in Bulgaria are more than 20 years old, with only 3.6 per cent of vehicles aged less than six years.
Sofia's municipal council is due to meet on January 25 to discuss more urgent measures to employ in days of extreme pollution -- like cheaper public transport tickets and limits on the entry of cars in the city centre.
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