User blog comment:Zippertrain85/The reasons why Serana is not from the First Era./@comment-1992639-20130519202102

My best guess for why Solitude looks so different is because of the East Empire Trading Company. They have had a foothold in Skyrim for probably quite some time, meaning they may have been behind a lot of the construction of the city. Similar to how old cities (and modern cities still) tend to grow when a seaport or airport is nearby, as a lot of people tend to centre around a place of work and trade.