Authorities closed the Acropolis for several hours on Tuesday over high temperatures as work restrictions remained in effect in other parts of Greece.
A Culture Ministry archaeological service announced the closure between 1pm and 5pm.
Mandatory work breaks were imposed in several other regions, mostly on islands and parts of central Greece, where temperatures exceeded 40C.
The measures started on Monday for outdoor workers.
Those who do not comply face a 2,000 euro (£1,728) fine per worker.
Authorities said the risk of wildfires, already “very high” across the eastern mainland, is expected to increase during the week.
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