An archaeological watching brief was conducted at Gonville and Caius College, Cambridge, during the instillation of a replacement gas supply. Investigations were undertaken within Caius Court and the southwestern portion of Tree Court. Although the trench was limited in depth, a number of results were obtained. Firstly, the footing of the College's 16th century eastern boundary wall was encountered. Originally constructed in 1565, this wall remained extant until 1854. In addition, part of the footing of the contemporary Gate of Virtue was also identified. Finally, within Caius Court a small finds assemblage was recovered from the 16th century and later made-ground deposits. This included pottery, glass, worked bone and clay tobacco pipe fragments.