"Beirut is a historic city."
Translation:بَيْروت مَدينة تاريخِيّة.
In Standard Grammar with full harakaat, Beirut (for the above sentence) will be:
بَيْرُوْتُ : bairuutu
مَدِيْنَةٌ : madiina /madiinatun
But, I assume that what you have heard is an audio glitch because Duolingo tried "hard" to remove all ending sounds and don't follow Standard Grammar totally.