Lego pieces of all varieties constitute a universal system. Despite variation in the design and the purposes of individual pieces over the years, each piece remains compatible in some way with existing pieces. Lego bricks from 1958 still interlock with those made in the current time, and Lego sets for young children are compatible with those made for teenagers. Six bricks of 2 × 4 studs[28] can be combined in 915,103,765 ways.[29]
Agent 13 has a pretty plain appearance, with caramel-coloured wavy hair, and a black, spy-like top. Her torso has some nice details, with sharp, angular lines that all combine to form a rough outline of an upside down star. She has plain sand blue pants and rocks a sub-machine gun accessory. I like regular LEGO firearms, so it’s very nice to get one in this set as they’re fairly uncommon.
The last of the three aircraft is a modern biplane. This incorporates a number of rare orange elements including right and left 8 x 3 wedge plates which make up the wings and have only previously appeared in three sets, a 3 x 4 wedge brick only previously found in two sets, and a 3 x 6 round half plate with a 1 x 2 cutout which has only previous appeared in a single set in this colour and which forms the tailplanes. Similar to the two jets the tail fin is stickered rather than printed, as are the pair of 1 x 4 x 1 panels making up the sides of the cockpit. Unlike the jets, however, the instrument panel is stickered, which seems odd as there are existing printed 1 x 2 light bluish grey tiles which could have done an acceptable job. There are also a pair of stickers which represent the engine exhausts and which are applied to a couple of modified 2 x 4 x 1 1/3 bricks with curved top which sit just behind the propeller; applying these neatly to the curved surface takes a steady hand, and that’s also the case for the pair of checkerboard stickers which are stuck onto the propeller cowl. As if stickered exhausts weren’t enough, there are also a couple of light bluish grey exhaust pipes with Technic pin which emerge from the propeller cowl and run along either side of the fuselage. They’re entirely superfluous given the presence of the stickered exhausts but they still look cool regardless!

The Lego Group began in the workshop of Ole Kirk Christiansen (1891–1958), a carpenter from Billund, Denmark, who began making wooden toys in 1932.[7][8] In 1934, his company came to be called "Lego", derived from the Danish phrase leg godt, which means "play well". In 1947, Lego expanded to begin producing plastic toys.[9] In 1949 Lego began producing, among other new products, an early version of the now familiar interlocking bricks, calling them "Automatic Binding Bricks". These bricks were based on the Kiddicraft Self-Locking Bricks, which had been patented in the United Kingdom in 1939[10] and released in 1947. Lego had received a sample of the Kiddicraft bricks from the supplier of an injection-molding machine that it purchased.[11] The bricks, originally manufactured from cellulose acetate,[12] were a development of the traditional stackable wooden blocks of the time.[9]

LEGO CITY has some recurring themes that can get old after a while and obviously are meant for younger LEGO fans.  The Fire and Police themes within CITY quickly come to mind as it seems like they have a new run each year.  The Airport theme is one of those that doesn't quite occur every year.  The last airport set was released in 2010 and was set #3182.  This year (2016) another airport was released.  #60104, Airport Passenger Terminal, was released on 1 August 2016 in the US.  It costs $99.99 in the US and contains 694 pieces or $0.144 per piece.  I picked the set up from Amazon at 20% off or $80 ($0.115 per piece).  Yay sales!  Onto the review...
Airport Passenger Terminal with control tower and conveyor belt measures over 11” high, 12” wide and 4” deep. Airplane measures over 7” high, 18” long and 19” wide. Service car measures over 1” high, 2” long and 1” wide. Luggage trailer measures over 3" long, 1" high and 1" wide. Fuel trailer measures over 1” high, 3” long and 1” wide. Mobile stairway measures over 2” high, 2” long and 1” wide
Parking capacity at Copenhagen Airport was greatly expanded in 2015 with the construction of a new lot as one of the first phases in an ambitious airport expansion plan scheduled to roll out in the coming decades. There are several lots: those near the terminals are very expensive, while the further-flung ones are cheaper (but have free shuttle bus service to the terminals).