To get high land value for zones, place a bunch of parks around the zone.

To have this cheat work you need to open the power plant menu and then close it using the X. Then open the rewards and opportunities menu and close it the same way. After that open the garbage disposal menu and close it the same way. Then go to the landmarks menu and all the buildings should be available.

At the main screen, load a city created by the CPU. Metropolis is the best for this. Play with it until you get a lot of money. Next, pause game play, and destroy the city with demolitions. Save with the name you want and start playing. You will start with all the inventions, millions in money and a totally empty terrain.
Note: This trick requires SimCity 2000. Create an empty SimCity 2000 city, then use the imacheat code from that game until you get the desired amount of money. Save the city, exit SimCity 2000, and open your .sc2 file in SimCity 3000 Unlimited. The game will import it, allowing you to start with extra money.
Choose Frankfurt, Germany and demolish and dezone everything using the i am weak code. Set the time to 'African Swallow' until the year 2057 so that pollution leaves. You can then make a city with 3,000,000 simoleons and no pollution.

Select a flat area on that map, use the terrain down tool, and click two times. Then use the level terrain tool and make a line 2 x 8 squares. Next, use the create surface water tool and fill the line to make a creek. Make a bridge over the creek. Next, choose the place pipe line tool but do not make pipe. Finally choose the level terrain tool and level the terrain under your creek when underground. Go aboveground and you will see that you have a bridge over the ground.

Select a new city. Use any terrain and build a city under pause. At the beginning, raise all tax to 10. Then lower all payments that you are paying the police etc. Lower them until you see that you are not in minus anymore. Then select play.

Enable the call cousin vinnie code, then deny it. He will say that it was a sting operation, then will give you the zyxwvu code. Enable this code to get the SimCastle in your rewards. Note: You cannot directly enable the zyxwvu code -- you must enable and deny the call cousin vinnie code first.

During game play press,SHIFT,CTRL,ALT,C
Evry thing is free:
(I am weak)
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To get Pop. Put streets in and run the
simulation
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THE END

Press [Ctrl] + [Alt] + [Shift] + C while in the simulator. A prompt box with a flashing cursor will appear in the top left corner of the screen. Type one of the following codes and press [Enter] to activate the corresponding cheat function.
Code Effect
call cousin vinnie $250,000 donation offer from Vinnie
i am weak All items are free
salt off Change the sea to fresh water
salt on Change the sea to salt water
i am weak Construction costs set to $0
the birds Create flock of seagulls
load terrain Load grayscale picture as terrain
terrain one down Lowers the terrain by one
terrain ten down Lowers the terrain by ten
terrain one up Raises the terrain by one
terrain ten up Raises the terrain by ten
traffic lights Reduced pollution and traffic
ufo swarm Set 'Disaster' to 'UFO' for unlimited UFOs
broccoli 'Sorry, Money Doesn't Grow On Broccoli' message
porntipsguzzardo 'Aha! We Have A Real Pro Here! Try BROCCOLI' message
bat 'Da Da Da Da Da Da Da Da Da BAT-man!' message
scurk 'If You Build It, They Will Come' message
llama 'The Llama Is A Quadruped' message
easter egg 'Duo Ragazzi's Easter Egg Palace: Old World Charm In A Post Modern Setting' message
sim 'If You Lived Here, You'd Be A Sim' message
help 'Dozens Of Hidden News Ticker Reveals; Sims Encouraged To Collect Them All And Amaze Friends' message
will wright 'What Will He Think Of Next?' message
erts 'Investment Tip: Buy Low, Sell High' message
electronic arts 'Not Just Sports Games Anymore' message
ticker '<city name> Picayune: The Finest In Scrolling Entertainment' message
money 'Money Does NOT Grow On Trees, Study Concludes' message
simcity 'Keep Trying And Maybe You'll Figure It Out' message
simon says 'Unknown' message
hello 'Greetings Mayor, Your Sims Salute You' message
mayor 'Mayor <mayor name> brings <city name> To News Ticker Highlight' message
sc3k 'Mayor Suspected Of Attempting Embezzlement; Ends In Failure' message
1234 'Secret Number Combination Causes Announcement In News Ticker' message
maxis 'Did you know that MAXIS spelled backwards is SIX AM?' message
moremoney 'MOREMONEY Not Cheat Code, Research Concludes' message
advisor 'Mayor Under Investigation For Possible Embezzlement' message
fund 'FUND Not A Cheat Code, Do Not Type MOREMONEY, It Is Not A Cheat Code Either' message
pay tribute to your king All extra rewards
power to the masses All power plants
water in the desert All water plants
i love red tape Description of City Hall set to 'Miles and Miles of Red Tape'; date set to the year 1900
nerdz rool High tech industries
garbage in, garbage out Recycling plant, waste to energy incinerator and normal incinerator
stop forcing advice Stops advice
force mortimer to say <phrase> Mortimer will say the indicated phrase.
force moe to say <phrase> Moe will say the indicated phrase.
force constance to say <phrase> Constance will say the indicated phrase.
force maria to say <phrase> Marla will say the indicated phrase.
force randall to say <phrase> Randall will say the indicated phrase.
force gus to say <phrase> Gus will say the indicated phrase.
force karen to say <phrase> Karen will say the indicated phrase.
force petitioners to say <phrase> The petitioners will say the indicated phrase.
let's make a deal If you have connections to your neighbors, they will start trying to make deals

Open and close out of the 'Power Plants' menu. Open and close the 'Rewards And Opportunities' menu. Open and close the 'Garbage Disposal' menu. Open the 'Landmarks' menu. All of the buildings are now unlocked in the menu.

Make a road away from your city, but connected. Place a low density industrial zone about 8x10 to 18x18, water it, then place a power line four squares away from the zone. Wait for the zone to develop, then pause game play and demolish any buildings you do not want. De-zone any zone that the farm is not using. Finally, make every building and field historical so other unwanted buildings will not take their place.

to unlock the cheat screen you just have to press and hold CONTROL,ALT,SHIFT,C then the cheat screen should appearto type in various cheats.