H.H. Scullard's From the Gracchi to Nero: A History of Rome 133 BC to AD 68 is another classic in this arena. A little more accessible than Syme's work, and not a bad intro.
It says how long ago something was said, so you can tell last month
from 2014 without doing the arithmetic. Full and green is recent; it
drains and cools as the date gets older, and empties completely at about
6 years.
6d5 days ago
8mo8 months ago
2yr2 years ago
4yr4 years ago
9yr9 years ago
A striped bar means the date itself is an estimate — the source did
not carry an exact one. An entry with no date at all gets no bar.