Carnival or Mardi Gras celebrations take place in many countries. There are Carnival celbrations in Greece in the weeks before the start of Lent, with the main celebrations the weekend before Lent starts. That weekend is followed by Clean Monday, when kites are traditionally flown.

• Clean Monday is a public holiday, so be prepared for extra busy (and perhaps full) ferries this weekend as Athenians head to the islands for a long weekend.
• The main festivities I have seen have been in the Plaka area of Athens on the last Saturday before Lent. Don't be put off if you are hit over the head with a plastic truncheon - the evenings I have been there the celebrations have been great fun and everyone has been very good-humoured. A tip - if you are carrying a plastic truncheon yourself you are likely to be hit harder than if you are not carrying a truncheon. I have never carried a plastic truncheon, but on year I called in to see the festivities on the way to the airport. As well as my rucksack I was carrying a plastic water bottle in a blue holder. I am sure many people mistook the bottle for a truncheon as I was whacked harder over the head than usual!
• In Naxos on the last Sunday before Lent ((or sometimes the Sunday before that) there is a carnival procession along the promenade. As well as watching the floats its is fun seeing the children in fancy dress.
• Also in Naxos, I have seen people in the villages dressed something like English Morris Men. These are Koudounati. There is more information at http://www.ellada.net/travelinfo/naxos.html