Madrid

You know a place is going to be good when WE visit 3 times in a row, but Madrid is a big city with 605km2 of area, and 12 metro lines, with ~12k bus stops. Madrid's beauty doesn't stop at the center, but it continues, from diverse neighborhoods such as Usera and Carnabachel, to one of the largest football stadiums, of course, the Santiago Bernabeu, hosting Real Madrid, but their rivals, Atletico Madrid, not too far away with the Metropolitano Stadium, which even though not opened in the 1900's, still gets a decent amount of people visiting it.

Madrid is #2 as the 2nd largest city in the European Union, after Berlin as #1 and its metropolitan area is the second-largest in the EU, after Paris. Madrid sits atop the River "Rio"/ "Manzanares".
They are about 660 m - 1000 m above mean sea level.