Of the many Buddhist monasteries to be found in the Kathmandu Valley, I Baha Bahi in Patan stands out as being an important architectural heritage. Among existing records relating is one which indicates it was founded in 1427. This article presents a reconstruction of the floor plan of I Baha Bahi based on a pre-restoration survey and on information gleaned in the course of the subsequent repairs and restoration work carried out. On the building. It was possible to draw several conclusions and these may be summarized as follows: I Baha Bahi is a quadrangle architecture. At one time, each wing was furni shed with a peristyle facing the courtyard to the rear of which was a corridor. The floor plan of I Baha Bahi as described here replicates that of the Cha Bahi in Kathmandu. However, at a later date the partition wall creating the corridor around the courtyard in I Baha Bahi was removed and replaced by lattice screens fitted into the intervals between the pillars forming the peristyle. The function of the rooms on the ground flooralso underwent a change: previously used as living quarters for resident priests, they came to be used to enshrine a pantheon of Buddhist images.