Perched high on the eastern slopes of Paris, the 20th Arrondissement has historically been a spot for local residents, with an emphasis on raucous music and hard-left politics. The few tourists who do broach the district usually get no farther than the Père Lachaise cemetery. Plentiful graffiti and one or two watch-your-step side streets attest to the area’s still-rough edges, but these are being smoothed over by growing clusters of dining and night life options.