It is located on the Great Hungarian Plain (Alföld) and it is the second largest city in Hungary (or third, when Miskolc attach a small village faster in a never ending race to become the 2nd).
"Who in his sane mind would build a city in the middle of a plain with no hill and no water?" -- once people asked about Debrecen, yet the city has grown into a vibrant center of culture, arts and science.
The city has had a rich history since its founding. It was the European center of Calvinism (it was called Calvinist Rome), and even served for a short time in the 19th century as the capital of Hungary.
The city is unfortunately quite off the center of the Hungarian traffic system (one railway and one highway - the number 4 - goes there), so it is time consuming to travel there from western Hungary. The government has plans to build the #3 (eastern) dual highway longer (or to build the #4 (south-eastern) dual highway, which does not even exist) and reconnect the city into the fast flow of traffic and economy.
There is a big University at Debrecen, called Debreceni Egyetem (www.unideb.hu)