There was a road that was about 2 km long between the two big buildings and the houses were all packed in along that road.
この場合、次のような言い方ができますよ。
ーThere was a road that was about 2 km long between the two big buildings and the houses were all packed in along that road.
「約2キロ長の道路が大きな２つの建物の間を走っていて、この道路沿いに住居が密集していた」
the houses were all packed in で「住居が密集していた」と言えます。
along that road で「その道路に沿って」
ご参考まで！
カナダ 
