text:  The residential area of Tikal covers an estimated 60 square kilometres ( 23 sq mi ) , much of which has not yet been cleared , mapped , or excavated . A huge set of earthworks discovered by Dennis E. <unk> and Donald Callender in the 1960s rings Tikal with a 6 @-@ metre ( 20 ft ) wide trench behind a rampart . The 16 square kilometres ( 6 @.@ 2 sq mi ) area around the site core has been intensively mapped ; it may have enclosed an area of some 125 square kilometres ( 48 sq mi ) ( see below ) . Population estimates place the demographic size of the site between 10 @,@ 000 and 90 @,@ 000 , and possibly 425 @,@ 000 in the surrounding area . Recently , a project exploring the defensive earthworks has shown that the scale of the earthworks is highly variable and that in many places it is inconsequential as a defensive feature . In addition , some parts of the earthwork were integrated into a canal system . The earthwork of Tikal varies significantly in coverage from what was originally proposed and it is much more complex and multifaceted than originally thought . 
  