Simplify the following text for a Grade 7 native English-speaking person.
Original: The last tram to pass through the central archway did so on 4 June 1938 , by which time part of Southampton ancient walls had been demolished so that the Bargate was passable on both sides .
Simplified: The last tram to pass through the central archway did so on 4 June 1938 . By this time part of Southampton ancient walls had been demolished so that the Bargate was passable on both sides .