Definite Article - yes or no?

Gap-fill exercise
Put in "the" if necessary or "NO" if the definite article is not necessary!

Fill in all the gaps, then press "Check" to check your answers.
Last year, Mr Brown, our history teacher, had to stay in hospital for six weeks. We visited him once in hospital in Glenn Close. Of course, we had lessons with our headteacher. We don't like her, and lessons she gives are really bad; so we were really glad when Mr Brown finally came back week before Christmas holidays. With him, History is really fun!
We talked a lot about ancient times, especially about time of the Roman Empire, and about war and peace. We heard that wars fought by the Roman Empereors were quite terrible. One of lessons was absolutely fantastic. When one of my classmates, Mark, asked Mr Brown if he could show us pictures of Roman castles, he took a book out of his desk and showed us a few of castles Romans built in country that is now Germany.