Visitor figures for many monuments in Greece have risen for a number of reasons:
Currently the country is seen as a safer (with regard to terrorists) destination than Turkey, Italy or Spain (Its worth noting that British Museum visitor figures have dropped by 30% since the London bombings).
Greece & its monuments have had a lot of recent publicity from the Olympics held in Athens last summer.
Also, as a result of the Olympics, many monuments are now more accessible to the disabled than they ever were previously.

From:
Kathimerini English Edition

Saturday August 13, 2005
Tourist numbers leap up
Expected double-digit rise confirms medium-term Olympics benefit
ANA

More tourists than ever are trekking up the Acropolis this year. After years of declining tourism revenues, Greece is bouncing back after the success of last year’s Olympics and more spending on advertising campaigns. The Games have also left a good legacy of better infrastructure, especially in Athens. The Acropolis is now accessible to the disabled via a small lift. However, Greece still suffers from many cases of substandard services in the tourism sector, which could leave visitors unhappy.

Tourist arrivals are expected to grow by double digits to over 14 million in 2005, much higher than previous forecasts indicated.

This rise reverses the falling trend which had prevailed between 2000 and 2003. There had been a slight increase in visitors in 2004 but the figures were disappointing to sector professionals, who had expected a boom thanks to the Athens Olympics.

The successful organization of the Games appears to be the main reason behind the rise in tourist arrivals, confirming predictions of medium- and long-term benefits. Tourism accounts for 20 percent of Greece’s GDP.

The recent attacks at tourist resorts in Turkey and terrorist threats against Italy and Spain appear also to have diverted a small number of tourist to Greece. Tourism industry representatives had estimated early this year that the number of arrivals would rise by 5-6 percent. A recent study by the National Bank of Greece had forecast a 7.5 percent increase, attributing it to a better marketing campaign by the state, along with the Games’ impact.

The marketing campaign for the 2005 season was increased more than threefold, to 31 million euros, over that for 2004, when only 9 million was spent despite that being the year of the Olympics. More importantly, this year’s campaign peaked at a time where most foreign tourists book their vacations, during the winter, and not later in the year, as used to be the case. For the 2006 season, Greece will spend 37 million euros in advertising. The campaign is expected to start as early as November and will be conducted in 42 countries, up from 28 last year.

Greece’s confirmation as a safe destination, cemented during the Olympics, has brought US tourists back in droves; in 2004 their numbers had already increased to 430,000 from 293,000 in 2003, a rise of 49 percent; a further 30 percent rise is expected this year. There has also been a significant increase in arrivals from Australia (25 percent), Italy (25 percent), Spain (25 percent), the Netherlands (15 percent) and Russia (15 percent). Still, the mainstays of the tourism industry are the British and Germans, who account for about half of all arrivals.

Not everything has been rosy, however. Outdated airports and ports, overpriced hotels and rooms offering services of inferior quality, and widespread price-gouging are turning a number of visitors off. A recent survey conducted among visitors to Athens found that 25 percent would not visit the city again, many because of the high prices and below-par service. And, despite the government’s boasts about its focus on tourism, organization in state services still lags. As one example, the program for the May-July events of the Athens Festival came out just last week.