Abstract: A modular bricklaying system comprises a control system and work unit(s). A method comprises receiving or determining reference marker(s) associated with a digital representation of a building site that keep the same position relative to the building site during building; receiving or determining digital representations of the work unit(s), a building plan defining a target position and laying order for each brick, and an initial position for some bricks; receiving position and pose information from one work unit, relative to the reference markers or the building site, and updating the digital representation of the work unit and the building site based on the received position and pose information; transmitting, by the control system, commands configuring the work unit(s) to apply mortar and lay bricks based on the digital representation of the building site and respective work units, the initial position of some of the bricks and building plan.