System LEGO System along with TECHNIC , is " The LEGO Company ' s " main line of building elements , minifigure s and sets , and features the iconic standard LEGO brick which evolved from LEGO ' s first series of Automatic Binding Bricks that first appeared in 1949 . The new pieces were first marketed under the name LEGO Mursten in 1953 and from 1955 to 1970 in the System i Leg series of toys . Later it was simply known as " LEGO System " . Most System bricks can be used with TECHNIC bricks . " LEGO System " is also the brand under which most standard minifigure - compatible sets are marketed since 1978 . The pieces in this line are smaller than DUPLO blocks . The iconic logo of " LEGO System " wasn ' t featured on boxes and catalogues until 1992 . Most newer minifigure - compatible sets no longer feature the logo , although they are still considered a part of " System " . The brick . The 1×1 - stud System - brick measures about 8×8×10 mm . The sizes of almost all other LEGO construction toys are derived from this size and can be combined with it . History . First minifigure - compatible themes ( 1978 – 1999 ) . With the introduction of minifigure - compatible sets in 1978 , three major playthemes were introduced , " Town " , " Castle " and " Space " , inside each of which were later added several new subthemes , that mostly consisted of new distinct factions of minifigures and were all related to the respective main theme ' s core subjects . With " Boats " and " Trains " , two minor themes where introduced that complemented " Town " but were not counted as parts or subthemes of it . Another unique theme was Model Team from 1986 , whose sets focused on more - or - less accurate scale reproductions of real - world vehicles and were not designed to be minifigure - compatible . Beginning with " Pirates " in 1989 , LEGO added additional main themes to the " LEGO System " line that stood beside the three initial main themes . These four major theme made up the bulk of the LEGO System sets of that era and were also the most popular themes . Another minor System theme , Belville , was introduced in 1994 , which contained larger figures and more specially - designed bricks . The next addition was " Aquazone " in 1995 followed by " Western " in 1996 . Another small theme , Time Cruisers , was introduced in the same year . The now six major minifigure themes ( " Town " , " Castle " , " Space " , " Pirates " , " Aquazone " and " Western " ) were subjected to bigger changes in 1999 : " Space " , " Pirates " , " Aquazone " and " Western " were discontinued . " Castle " was rebranded to " Knights ' Kingdom " . " Town ' s " core subjects were outsourced to " Town Jr . " and later " City Center " , while still being complemented by different subthemes which were in most cases only remotely related to city life . An exception was the smaller " Adventurers " theme from 1998 that was complemented with different subthemes until its eventual discontinuation in 2004 . The smaller Alpha Team was introduced in 2001 and lasted several years longer than most other themes . Smaller themes and licensing ( 1999 onwards ) . Small themes . Instead of slowly adding new factions and sets to existing main themes , most themes were now self - contained series of sets that , in most cases , had all of their sets released within the first year and only lasted for one or two more years . One of these new themes was " Rock Raiders " from 1999 and " Life on Mars " from 2001 , a short - lived revival of the old " Space " theme . Licensed System sets . The other side of the medal were themes that were based on popular media franchises like " Star Wars " and " Harry Potter " . Those themes would regularly see new releases over the timespan of several years . Another possibility of releasing sets based on licenses was the " Studios " theme . Nevertheless , there were still some original LEGO themes that ran for several years and were regularly updated with new sets , like " Alpha Team " , which ran from 2001 to 2005 , and to a lesser extent " Knights ' Kingdom II , " which saw new releases from 2004 to 2006 . Relaunch of classic themes ( 2005 onwards ) . With the introduction of " City " in 2005 , the constant rebranding of the " Town " theme in the years after 1999 came to a halt . It also marked the first true revival of one of the classic major themes , and the initial concept of complementing a consistent , long - running theme by regular releases of new sets saw a renaissance as well . Other recent themes were " Castle ( 2007 ) " and the continuation of " Pirates " . " Space " saw a partial revival in the form of " Mars Mission " ( 2007 – 8 ) and the new " Space Police " from 2009 .