In 1956, LEGO released 24 sets across 2 themes, all of these sets have been retired.
Most valuable 1956 LEGO set
700-5-2 Gift Package $3,653.89
Largest 1956 LEGO set
700-0 Town Plan System 264 pieces
Most owned 1956 set
231-2 Esso Pumps and Sign
Throughout 1956, LEGO expanded its Mursten and System i Leg themes, simplifying designs by removing older panel-style windows and slotted bricks. New sets included a VW Van, Cyclists/Motorcyclists, Traffic Police, and an Esso Filling Station. Most releases were supplementary sets, with individual bricks sold only in Denmark and some were also available in Sweden and Norway.
24 sets

224 2x2 & 2x4 Curved Bricks

Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 14
Availability Retired
224 LEGO 2x2 & 2x4 Curved Bricks
Retail $0.50

231-2 Esso Pumps and Sign

Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 2
Availability Retired
231-2 LEGO Esso Pumps and Sign
Retail $0.50
Value $125.21
Growth  +24942.0%
Annual growth 9.5%

236 Garage with Automatic Door

Theme / Subtheme System i Leg / Town Plan
Year 1956
Pieces 69
Availability Retired
236 LEGO Garage with Automatic Door
Retail $3.25
Value $346.78
Growth  +10570.2%
Annual growth 7.0%

250-2 1:87 Esso Bedford Tanker

Theme / Subtheme System i Leg / HO 1:87 Vehicles
Year 1956
Availability Retired
250-2 LEGO 1:87 Esso Bedford Tanker
Retail $1.15
Value $255.57
Growth  +22123.5%
Annual growth 8.2%

251-2 1:87 Esso Bedford Truck

Theme / Subtheme System i Leg / HO 1:87 Vehicles
Year 1956
Availability Retired
251-2 LEGO 1:87 Esso Bedford Truck
Retail $1.95
Value $210.96
Growth  +10718.5%
Annual growth 7.0%

252-2 1:87 Esso Bedford Trailer

Theme / Subtheme System i Leg / HO 1:87 Vehicles
Year 1956
Availability Retired
252-2 LEGO 1:87 Esso Bedford Trailer
Retail $0.70

275-2 1:87 VW Van

Theme / Subtheme System i Leg / HO 1:87 Vehicles
Year 1956
Availability Retired
275-2 LEGO 1:87 VW Van
Retail $0.70
Value $349.45
Growth  +49821.4%
Annual growth 8.9%

700-0 Town Plan System

Theme / Subtheme System i Leg / Town Plan
Year 1956
Pieces 264
Availability Retired
700-0 LEGO Town Plan System

700-2-1 Gift Package

Theme / Subtheme Mursten / Basic Set
Year 1956
Availability Retired
700-2-1 LEGO Gift Package
Retail $3.50

700-2-3 Gift Package

Theme / Subtheme Mursten / Basic Set
Year 1956
Availability Retired
700-2-3 LEGO Gift Package
Retail $3.25

700-3-2 Gift Package

Theme / Subtheme Mursten / Basic Set
Year 1956
Availability Retired
700-3-2 LEGO Gift Package
Retail $2.50
Value $3,059.39
Growth  +122275.6%
Annual growth 10.9%

700-3A-2 Gift Package

Theme / Subtheme Mursten / Town Plan
Year 1956
Availability Retired
700-3A-2 LEGO Gift Package
Retail $3.25
Value $1,994.23
Growth  +61260.9%
Annual growth 9.8%

700-4-3 Gift Package

Theme / Subtheme Mursten / Basic Set
Year 1956
Availability Retired
700-4-3 LEGO Gift Package
Retail $1.50
Value $2,681.33
Growth  +178655.3%
Annual growth 11.5%

700-5-2 Gift Package

Theme / Subtheme Mursten / Basic Set
Year 1956
Availability Retired
700-5-2 LEGO Gift Package
Retail $1.25
Value $3,653.89
Growth  +292211.2%
Annual growth 12.3%

700-6-2 Gift Package

Theme / Subtheme Mursten / Town Plan
Year 1956
Pieces 46
Availability Retired
700-6-2 LEGO Gift Package
Retail $2.25
Value $2,245.38
Growth  +99694.7%
Annual growth 10.5%

1200-2 Town Plan Board Small Plastic

Theme / Subtheme System i Leg / Town Plan
Year 1956
Pieces 1
Availability Retired
1200-2 LEGO Town Plan Board Small Plastic
Retail $4.00
Value $293.90
Growth  +7247.5%
Annual growth 6.4%

1226-2 6x8 & 2x8 Plates

Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 4
Availability Retired
1226-2 LEGO 6x8 & 2x8 Plates
Retail $0.50

1227-2 4x8 & 2x8 Plates

Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 5
Availability Retired
1227-2 LEGO 4x8 & 2x8 Plates
Retail $0.50

1228-2 4x8 Curved & 2x8 Plates

Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 6
Availability Retired
1228-2 LEGO 4x8 Curved & 2x8 Plates
Retail $0.50

1231-2 Red Windows and Door with Glass

Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 10
Availability Retired
1231-2 LEGO Red Windows and Door with Glass
Retail $1.00
Value $1.49
Growth  +49.0%

1231-3 White Windows and Door with Glass

Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 10
Availability Retired
1231-3 LEGO White Windows and Door with Glass
Retail $1.00
Value $1.49
Growth  +49.0%

1270 5 Cyclists / Motorcyclists

Theme / Subtheme System i Leg / HO 1:87 Vehicles
Year 1956
Pieces 5
Availability Retired
1270 LEGO 5 Cyclists / Motorcyclists
Retail $2.00
Value $310.73
Growth  +15436.5%
Annual growth 7.6%

1271-2 Traffic Police Set

Theme / Subtheme System i Leg / Town Plan
Year 1956
Pieces 6
Availability Retired
1271-2 LEGO Traffic Police Set
Retail $1.25
Value $209.39
Growth  +16651.2%
Annual growth 7.7%

1310 ESSO Filling Station

Theme / Subtheme System i Leg / Town Plan
Year 1956
Pieces 96
Availability Retired
1310 LEGO ESSO Filling Station
Retail $3.75
Value $3,229.51
Growth  +86020.3%
Annual growth 10.3%