Halacha forbids going out of one's way in a conspicuous manner to visit his business on Shabbat, for the purpose of supervising or analyzing the operation. By the same token, if a person has a house being built, he may not go visit the construction site on Shabbat to look and analyze the plans for the project. If, however, he is walking and passes by the construction site, then he may look at the site and think about the construction; Halacha forbids only going out of one's way to look upon the building site. (Menuhat Ahava)
