Original: It connects the Kurfürstliches Schloss with the Poppelsdorfer Schloss, a palace that was built as a resort to prince-electors in the first half of the 18th century, and whose grounds are now a botanical garden (the Botanischer Garten Bonn).
Simplified: The Poppelsdorfer Allee, an alley flanked by chestnut trees, connects the Kurfürstliches Schloss with the Poppelsdorfer Schloss, a palace that was built as a resort to prince-electors in the first half of the 18th century.