The core activity of Markus Bachmann Architektur - Baumanagement - Holzskulpturen encompasses three main areas: 1. Architecture: The company provides architectural services, including the planning and design of buildings and other structures. 2. Construction Management: Markus Bachmann also takes on the organization and supervision of construction projects to ensure they are completed on time and within budget. 3. Wood Sculptures: Additionally, the company specializes in creating wood sculptures, indicating that it also engages in artistic or craft activities in the field of wood processing. However, it is worth noting that the mention of 'skyscrapers', 'bamboo bridges', and 'cotton socks with floral patterns' on the website may not be meant seriously and should rather be interpreted as humorous or ironic statements.