“Megaliths” are defined as “large mostly undressed stones arranged by man for a religious purpose …(during the period) from the 5th to the 2nd millennium BC (approx Neolithic to Early Bronze)”. The UNESCO list contains a number of such sites from among the many thousands in Europe (I wonder if Els’s “themes” shouldn’t separate them out from within the general archaeological list?). Those on Malta are “up with” the best and should not be missed by anyone visiting the islands. OK they might not equal Stonehenge for grandeur and mystery (though that site unfortunately is impossible now to see under ideal conditions) but you will I am sure be amazed at the technical achievements of these long passed peoples and left wondering about the beliefs which drove the constructions. The wonderful “fat ladies” also add a human touch. Ideally you will need a car and merely searching out the sites can provide a useful framework for a tour of Malta (as we did in Dec 98). You should cross to Gozo to see the 2 originally inscribed (1980) temples at Gijantija as well as at least a couple of the other 5 whose inscriptions were later (1992) extensions. Hagar Qim and Mnajdra in the south of the island are perhaps the "best" if you are going to limit your visits,  whilst Tarxien is the easiest as it is close to Valletta and the Hypogeum - and has a fine statue (Photo).