Alphabet

Requirements
Alphabet costs 30 science

1 Science: 30 turns until complete

2 Science: 15 turns until complete

3: 10

4: 8

5: 6

6-7: 5

8-9: 4

10-14: 3

Leads to
Alphabet leads to Calendar and Writing, which makes it useful for getting religious, economic, and scientific technologies.

Unlocks
Alphabet allows trading technologies, which can really help if you are behind!