His studies took him on extensive trips over Europe to study the art of the great masters Sitte, Stuebben, Baumeister, Hausmann and others. He visited the medieval cities of Nuremberg, Rothenburg, Regensburg and others, all of which showed that the Romans, who laid the original foundations of these cities, had certain definite knowledge of city planning. However, these early city planners did not impart their theory but left only their accomplishments as a record of their work. It remained for the Germans to place the art of city planning on a scientific basis, and realizing the great benefits derived, other countries fell into line, following the system established by the Germans. During his travels Carl did not fail to visit the ancient Roman and Greek cities, where the remains of once great structures and roadways testify to the skill of the city builders. While L’Enfant, who planned the city of Washington, admittedly the most beautiful city of America and one of the finest in the world, enjoyed the double good fortune of having the support of the founders of the Republic and an unencumbered site upon which to build, the problem in most cases today is to replace existing cities and provide for future developments. Upon his return to America, Carl located in New York, opening an office as consulting engineer and advisory city planner. He applied his knowledge to getting “hard cash,” but he very often worked for little or no compensation. It did not matter to him--all he wanted to see was the ultimate result. His reputation as a successful engineer and writer became widespread, with the result that he was besieged from all sides with requests to engage in industrial campaigns and the like. Quite a number of concerns owe to him and his writings the fact that they got out of the rut and were able to re-establish themselves on a sound financial basis. To him, also, came concerns with shady reputations in the hope that he would lend the weight of his name to their prospectuses. But they were politely requested to seek such assistance elsewhere. But city planning was his forte. It appealed to him as did no other work. He recognized the great opportunity for the replanning of American cities, so long neglected with such costly results as are seen in the unnecessary congestion and crowded conditions of some portions and the backward development of others--in the slums on one hand and the inaccessible suburbs on the others--so characteristic of the majority of our cities. The citizens of a small town never imagine that it will become a large city. They may, at times, dream of it as spreading out around the nucleus in which they live and they may frequently boast of the progress their town has made in the previous decade, but the day that will see their town a great city seems so far distant that, as a rule, they do not imagine it will ever occur.