建筑材料决定了建筑风格和文明

正在欧洲旅游。英法的那些用方块垛子建造的建筑物太宏伟了。这种东西不像现代的水泥，似乎还能雕刻。查了一下，水泥是在公元1800左右发明的。这个时期中国的建筑似乎还是砖木结构，没法造的这么高大坚固。我有个1926年建造的房子。一次把后院门的台阶打碎，灰白色，不像现代水泥那么硬，应该也是那种材料。

The cathedral suffered fourteen hits by aerial bombs during World War II. Badly damaged, it nevertheless remained standing in an otherwise completely flattened city. 

https://en.wikipedia.org/wiki/Cologne_Cathedral

The German city of Cologne was bombed in 262 separate air raids[1] by the Allies during World War II, all by the Royal Air Force (RAF). A total of 34,711 long tons of bombs were dropped on the city by the RAF.[2] 20,000 civilians died during the war in Cologne due to aerial bombardments.[3]

While air raid alarms had gone off in the winter/spring of 1940 as British bombers passed overhead, the first bombing took place on 12 May 1940.[4] The 30/31 May 1942 attack on Cologne was the first 1,000 bomber raid.

https://en.wikipedia.org/wiki/Bombing_of_Cologne_in_World_War_II

说是某个人的善心，在一千架轰炸机的轰炸里面，渺小了许多。

这篇文章说，罗马混凝土里面有生石灰，这样出现裂缝进水后，生石灰遇水有自我补救的功能。

https://www.scientificamerican.com/article/ancient-roman-concrete-has-self-healing-capabilities/

Mineral deposits called “lime clasts” found in ancient Roman concrete give the material self-healing capabilities