What is the fine-grained topic of the following text: In 1927 a study by Alexandru Davidescu was published at the Polytechic School and two years later the Romanian Parlament passed the law number 2749 on the building of Arges-Danube channel and of a port in Bucharest published in "Monitorul Oficial" in August 1929. Only return the topic.
The building of the Arges-Danube channel and a port in Bucharest in the late 1920s.