Ordinarily we use the simple present to express current states, not current events—especially telic events, events which have a goal 'built in' to the sense of the verb. If the event is still in progress, we use the progressive construction:
A new school is being built in our city.
If the event is complete, it is no longer current, so we use the perfect:
A new school has been built in our city.
This rule is relaxed with activity verbs, events which have duration but no built-in goal:
The Mississippi river runs past our city.
The 4th of July is celebrated every year in our city.
But even here the progressive is preferred if the activity is seen as temporary, as having a foreseeable end:
The 4th of July is being celebrated now in our city.
The simple present is used for singular (non-repetitive) events only in a handful of circumstances:
In live-action narration—for example, the broadcast of sports events:
He shoots, he scores!
In chronicles and headlines:
1066 – William of Normandy conquers England.
1215 – Magna Carta is imposed on King John.West Side resolution: hostages are released.
In synopses of the action of works of fiction and drama:
Spain is torn apart by Civil War. The commander of the Royalist Aragon troops, Count di Luna, is obsessed with Leonora, a young noblewoman in the queen’s service, who does not return his love.