France–Germany relations of the further integration of the EU. They are sometimes described as the "twin engine" or "core countries" pushing for moves. A tram straddling the Franco-German border, across the river Rhine from Strasbourg to Kehl, was inaugurated on the 28th of April 2017 symbolising the strength of relation between the two countries. Both France and Germany track their history back to the time of Charlemagne, whose vast empire included most of the area of both modern-day France and Germany – as well as the Netherlands, Belgium, Luxembourg, Switzerland, Austria, Slovenia, and northern Italy. The death of Charlemagne's son Louis the
Locked Out of Heaven debuted at number 32 in Denmark, becoming Mars' fifth top-fifteen single in the country and peaked at number two, spending one week. "Locked Out of Heaven" peaked at number seven in Germany. "Locked Out of Heaven" peaked at number eight in Norway and Switzerland, six in Sweden, and 11 in Finland. "Locked Out of Heaven" entered the New Zealand Singles Chart at number 23 on October 15, 2012. After five weeks the song jumped in the top ten, to number eight, remaining for two weeks, before climbing to number six. Eventually, the song peaked at number four after four weeks.