 Many other forts like the Vattakottai Fort facing the sea near Kanyakumari, the hill-forts of Savakkotta, and the Marunnu Kotta (Ammunition fort) near Padmanabhapuram were built under De Lannoy's supervision.De Lannoy is also credited with the erection of some other small forts and tunnels.As a Christian, De Lannoy was prohibited from entering the king's palace at Padmanabhapuram so he resided primarily at Udayagiri Fort, or "De Lannoy Kotta" (de Lannoy's Fort) as it is known locally, where he also built a small chapel for his family and other Christians.