Simplify the following text for a Grade 4 native English-speaking person.
Original: Administratively , Bratislava is divided into five districts : Bratislava I ( the city center ) , Bratislava II ( eastern parts ) , Bratislava III ( north-eastern parts ) , Bratislava IV ( western and northern parts ) and Bratislava V ( southern parts on the right bank of the Danube , including PetrÅ 3\/4 alka , the most densely populated residential area in Central Europe ) .
Simplified: Bratislava had many names through its history .