Did you know that Pest as a city that joined Buda and Óbuda in 1873 was very small compared to the current size of the Pest side of Budapest? The city stretched within the boundary of Museum avenue (Small boulevard), roughly between the Liberty bridge and Chain Bridge. In medieval times the cities were surrounded by walls, Pest was not an exception, especially after the Tatar-Mongol attacks.
The first wall was erected around Pest in the 13th century, but it was soon deconstructed. Another wall around Pest was built a century later, and it lasted until the 18th century when the decision was taken to demolish it, as the offense was already much stronger than the defense, and the wall became redundant. The wall was 6 to 9 meters tall (if you count battlements on the top) and 2 meters wide.
The residents of Pest were practical people, they decided to keep some parts of the wall and incorporate them into the new walls of the buildings that were constructed. Therefore, even if you cannot find medieval buildings in Pest, you can at least still find pieces of wall here and there, hidden in the courtyards or Mercure hotel parking garage or next to Csendes bar. There is even a wall museum in Bástya St. The longest (50) and most accessible part of the wall that you can see in the picture, is easily accessible after the renovation and opening of a brand new playground next to it in 2022.