A bomb has exploded outside a ship owner's house near the Acropolis in central Athens, causing damage but no injuries.
The explosion near the country's most famous monument followed a warning call to a Greek newspaper.
There was no immediate claim of responsibility for the blast, which follows a string of bomb attacks in the financially-struggling country by anarchist groups that have caused no major injuries or loss of life.
Police spokesman Panagiotis Papapetropoulos said officers were able before the blast to evacuate one or two people from the building and to seal off the area.
"Judging by the minor extent of the damage, it can't have been a very strong explosive device," he said.
The house belongs to a member of the Tsakos ship owning family.
The blast, which was heard across the city centre, occurred very close to one of the Greek capital's favourite pedestrian walks that skirts the key tourist site of the Acropolis. At the time of the explosion, the walkway was busy with strolling families and tourists.
Greece is suffering an acute financial crisis and imposed deeply-resented austerity measures over the past three years to secure international bailouts that are shielding it from bankruptcy. Domestic anarchist groups have carried out dozens of attacks on police and other symbols of state authority or wealth in recent years, especially following the 2008 fatal police shooting of an Athens teenager and during the financial crisis.
The attacks have continued, albeit slightly abated, despite the arrests of more than 20 young Greeks accused of belonging to the most active group - Conspiracy Nuclei of Fire.
Earlier this month, militant anarchists claimed responsibility for a bombing at a package shipping firm in Athens and threatened further attacks on judges, police and prosecution witnesses in a terrorism trial. In January, another such group planted a bomb in an Athens shopping mall that wounded two security guards.