Short answers, pulled from the story.
The Roman Empire began in 27 BC when the Senate bestowed upon Octavian the titles Augustus and Princeps. Octavian, also known as Augustus, became the first emperor after defeating Mark Antony at the Battle of Actium in 31 BC.
Caligula succeeded Tiberius in 37 AD at the age of twenty-four before being assassinated by Cassius Chaerea in 41 AD along with his wife Caesonia and daughter Julia Drusilla. The Senate briefly debated restoring the Republic following his death but instead acclaimed Claudius as emperor.
Vespasian funded public works including the Amphitheatrum Flavium later known as the Colosseum and built the Forum of Vespasian featuring the Temple of Peace as its centerpiece. His son Titus held opening ceremonies for the unfinished Colosseum in 80 AD with a show lasting one hundred days.
The period known as the Five Good Emperors began when Nerva adopted Trajan as successor in October 97 AD and ended with Marcus Aurelius dying in 180 AD. This era includes Nerva, Trajan, Hadrian, Antoninus Pius, and Marcus Aurelius who wrote Meditations during the last years of his life.
Most chronologies place the final collapse of the Western Roman Empire in 476 AD when Romulus Augustulus was forced to abdicate to Germanic warlord Odoacer. The Eastern empire survived over a millennium longer until 1453 when Constantine XI died following the fall of Constantinople to Ottoman Turks.