Improving tiles with Colossal Heads may be a wise strategy for those who are seeking a Religious Victory. With a large number of these improvements being worked, you will generate a lot of Faith per turn.
The colossal "Olmec Heads," 17 stone sculptures dating to before 900 BC, are the best known remnants (at least, by tourists) of the once flourishing Mesoamerican Olmec civilization. Carved from a single boulder and then transported many miles, each depicts the head and face of a mature man, likely that of a powerful Olmec ruler, or as some theories would have it, famous ball players (if so, not much has changed). The massive heads weigh between six (the smallest) and 50 tons (the largest, but unfinished), made from basalt from quarries in the Sierra de los Tuxtlas range near Veracruz. Given that the Olmec had no metal tools, the effort to scatter these sculptures across the countryside was immense ... yet another instance of mankind's desire to leave their mark on the world.