This paper addresses the challenge of enhancing the performance of fired clay bricks and masonry, which are among the oldest and most widely used building materials globally by modeling the relation between (micro-)structure and (macro-)properties. Modern bricks and masonry is an engineered construction material with varying clay composition, block design, and mortar joints. To address the complexity, the paper reports on a micromechanics multiscale material model for predicting the mechanical behavior of fired clay. This model considers mineral grains, pores, and matrix phases across different observation scales, utilizing morphometry and mechanical input data from various experimental techniques including mercury intrusion porosimetry, micro-computed tomography, nanoindentation, and SEM-EDX. The study also employs three-dimensional finite element models to predict the failure of vertically perforated fired clay blocks, incorporating discrete crack modeling and mortar joint reinforcement analysis. The findings contribute to a better understanding of the relationship between brick geometry and strength properties, identifying potential benefits of mortar joint reinforcement.