Here is the full list of all 61 Metropolis achievements.
You created a new mayor
Your population exceeds 40,000
Your population exceeds 50,000
Your population exceeds 60,000
Your population exceeds 75,000
Your population exceeds 100,000
Your population exceeds 150,000
Your population exceeds 250,000
Your population exceeds 500,000
Your population exceeds 1,000,000
Your population exceeds 1,500,000
Your population exceeds 2,000,000
Your city has risen to 19th
Your city has risen to 18th
Your city has risen to 17th
Your city has risen to 16th
Your city has risen to 15th
Your city has risen to 14th
Your city has risen to 13th
Your city has risen to 12th
Your city has risen to 11th
Your city has risen to 10th
Your city has risen to 9th
Your city has risen to 8th
Your city has risen to 7th
Your city has risen to 6th
Your city has risen to 5th
Your city has risen to 4th
Your city has risen to 3rd
Your city has risen to 2nd
Your city has risen to 1st
You have built 1 building
You have built 5 buildings
You have built 10 buildings
You have built 15 buildings
You have built 20 buildings
You have built 30 buildings
You have built 40 buildings
You have built 50 buildings
You have built 60 buildings
You have built 75 buildings
You have built 100 buildings
You have built 150 buildings
Residents are happy with traffic levels
Residents are happy with crime level
Residents are happy with the number of jobs
Residents are happy with the level of pollution
Residents are happy with healthcare
Residents are happy with education
Residents are happy with low tax levels
Residents are happy with housing
Residents are happy with the environment
Residents are happy with leisure
You have won 1 election
You have won 2 elections
You have won 3 elections
You have won 4 elections
You have won 5 elections
You have won 6 elections
You flew a drone above the city