Short answers, pulled from the story.
A capital city is the municipality holding primary status in a country, state, province, department, or other subnational division, usually as its seat of government. It typically encompasses the government's offices and meeting places, with its status often designated by law or a constitution.
Damascus is the earliest capital still in existence, having existed since around 2500 BC.
The word capital derives from the Latin caput, genitive capitis, meaning 'head', later borrowed from the Medieval Latin capitalis, meaning 'of the head'. The poet Ovid used the phrase Roma Caput Mundi as early as the 1st century BC.
South Africa has three capitals: Pretoria for administration, Cape Town for legislation, and Bloemfontein for the judiciary. The Canary Islands hold two capital cities, Santa Cruz de Tenerife and Las Palmas de Gran Canaria, the only autonomous community in Spain with two capitals.
Washington, D.C. was founded as a compromise between more urbanized Northern states and agrarian Southern slave states to share national power. The Compromise of 1790 led to the Residence Act, which approved a national capital on the Potomac River on land ceded from Maryland and Virginia.
A capital city is usually a primary target in war because capturing it generally guarantees capture of much of the enemy government and victory for the attacking forces. In ancient China, a dynasty could be toppled with the fall of its capital, as when Shu and Wu fell with Chengdu and Jianye.
Plymouth in Montserrat is a ghost town that is currently the de jure capital of its territory.