The Maya culture flourished in the area which extends from the Yucatan to south-east Mexico, Belize, Guatemala and Honduras. Between the third and the ninth centuries AD - the so called Classic - hundreds of Maya city states developed here; among them, one could mention world-famous places like Tikal and Palenque. Most of these classical cities rapidly collapsed, for unclear reasons. However, in the subsequent or Post Classic period, equally wonderful towns developed in the Yucatan lowlands, such as for instance, Uxmal and Chichen Itza. Maya city-states were autonomous, but some were linked by mutual alliances, while others were engaged in ferocious wars. The political dependence between cities was in many cases celebrated with the construction of a sacbé. Sacbeob are ceremonial straight roads, running on an artificial platforms and endowed with monumental archs. Some sacbeob connect sacred areas of the same town, but others are very long, and the longest known – connecting Coba' to Yaxuna' – extend as much as 105 kilometres. The political history of the Maya cities has gradually been revealed in the last few decades, thanks to the progressive deciphering of the inscriptions. The Maya culture and religion were extremely complex. Their tiered cosmos was structured in three levels. The underground world had an intricate geography and was divided into nine sub-levels. The heavenly world was populated mainly by gods associated with natural phenomena, and in particular Chac, the Rain God In the sky, Venus was associated with Chac and played a important role, so that her cycles were studied accurately. More generally speaking, the prediction of all cosmic events and the study of their presumed influence on human lives was of fundamental significance for the Mayas. In particular, they developed sophisticated tables for studying the periods of time in which eclipses were likely to occur, as testified to by the few Maya books that have come down to us. Of course, astronomy and astrology were linked in these texts, since celestial events were connected with rituals and omens. As a consequence, it has often been said that the Mayas were obsessed by the calendar, and many ridiculous attempts were made to stir up a similar obsession to us on the occasion of December 2012. In reality, the Maya were “obsessed” only insofar that calendrics was an essential ingredient of the timing of Maya agricultural activities as well as of their social and religious life, from the choice of the name of a newborn to the festivities connected with the completion of time cycles. Many reflections of this can be seen in Maya Architecture, so it is important to understand how Maya calendar cycles were working. The Mayas used three different, parallel calendars: the Tzolkin, the Haab, and the Long Count. The Tzolkin combines a cycle of twenty named days with another cycle of thirteen numbers for a total of 260 days The reason for the choice of 260 days is unknown; but there are two astronomical periods which (more or less exactly) last 260 days. The first is the interval between two zenith passages at the latitude of the Maya city of Copan. As a consequence, Copan has been repeatedly proposed as the place where this calendar was devised. The other possible astronomical interpretation relates to the Venus cycle, since the period of visibility of Venus as the Morning Star is about 258 days. However in both cases the 260 days are only a part of a complete astronomical cycle: therefore they cannot be used for an astronomically anchored calendar. The Haab consisted of 18 months of 20 days each, plus five days considered to be inauspicious, making a total of 365 days, without any correction such as leap year. Clealry the Maya were aware that 365 days is a very bad approximation of the length of the solar year, but – like the Egyptians – were not interested to keep the calendar in sync with the seasons. Since 73 cycles of Tzolkin days equal 52 haab years, every 52 years a “calendar round” date occurred, a coincidence of the two calendars, which was an important occasion for the Mayas, they celebrated with rebuilding of temples and human sacrifices. Finally, we have yet to understand the working of the long-term calendar or Long Count. Observe first that our dates are made up of 3 numbers: days, months and years. For us, the days go from 1 to at most 31 and then start again, the months go from 1 to 12 and then start again, but the years go on ad infinitum. So, only the first two numbers are recursive: the first of January for instance comes again, but the year changes. A Long Count Maya date was made up of five numbers, instead of three. These numbers count days (k'ins), months of 20 days (uinals), years of 360 days (tuns), periods of 20 tuns (k'atuns), and periods of 20 k'atuns (b'ak'tuns). The main difference with our calendar however is that all the entries were recursive. Thus, all possible Long Count dates, consisting of five numbers in succession, were finite in number. A complete Long Count period ends with the 13 b'ak'tun, after 5 125 solar years from the beginning. Of course, to match a Maya date with a Gregiorian one we must find at least one correspondence. Fortunately, this can be done on the basis of historical documents, and we know that the starting date of the Long Count was August 13th, 3 114 BC. It can be inferred from this that the end of the 13 b'ak'tun and therefore the re-start of the Maya calendar was at the winter solstice 2012. The catastrophe theories linked to this (besides proving to be false on December 22) find no justification in the extant Maya documents and records. Obviously, however, a very interesting issue remains on the table and ‒ as far as I know ‒ it is totally unaddressed: that of understanding the reasons behind the choice of the starting date, as well as the length of the recursive period.