On the Pisan Mountains that divide the plain of Pisa from that of Lucca, there are many paths suitable for MTB and especially trekking.
One of these has a particular historical-literary value, because it would have been traveled by no less than Dante Alighieri: it is precisely the Passo di Dante, who in the Comedy at canto XXXIII of the Inferno refers "al monte per che i Pisan veder Lucca non ponno." (ie the mountain that prevents the view of a city from the other one.) Above the stone slab that bears these verses, there is a bust of the Poet.
Naturally this pass, that connected the Lucca side with the Pisan one, was well known long before Dante: from the Neolithic to the Roman age it had been traveled by people of all origins, but from the Renaissance onwards it was known just as "Dante's Pass".
The tour up to the Pass, which is located just over 200 m above sea level and offers beautiful landscape views of Pisa, can be started from S. Maria del Giudice or S. Giuliano, with distances that vary depending on the starting point and if you go to on foot or by bike.