Guardian: The ruins lie silent and abandoned in the heart of the jungle; blocks of stone surrendered to the vines, which twist and writhe over temples, plazas and pyramids. Weeds and forest creatures have colonised the inner sanctums; mahogany and cedar trees swallow what once were roads, blotting out the sun. This is Tikal, the ancient Mayan city of northern Guatemala. There was a time when tens of thousands of people lived here. The architecture and urban planning – there are epic monuments, …