> I wasn't expecting to see so many tall buildings.

Ancient Rome already had lots of tall buildings. https://imperiumromanum.pl/en/curiosities/roman-skyscrapers/

“But where the population is increasing rapidly and the city area is not, this traditional Roman house is disappearing. Due to lack of space, insula grows not outwards but upwards.

Already in the 3rd century BCE, most of these buildings have three floors - and will soon cross this barrier. Insula was supposed to generate profit for the owners- hence they were built very quickly, cheaply and very messily. Collapses or fires in insulae occurred more often than often. Hence the attempt to limit the height of Roman buildings by subsequent emperors, for example, Octavian Augustus (maximum height 70 pes, Roman feet, just over 20 meters; 1 pes = ca 44.5 cm) or Trajan.

After a great fire in Rome, Nero limited its height to 60 pes. These restrictions did not apply in other cities of the empire, hence the surprise of the famous Strabo, that in the mentioned Tire the insulae are almost as impressive as in the capital.”