Angra dos Reis is the main hub for boats to Ilha Grande. I got a bus to the town from Rio de Janeiro, walked from the bus station to the docks, and got on a boat to Ilha Grande within a few minutes. That didn’t leave me with much time to see the town, but I was able to at least observe a lot during my 15 minute walk from the bus station.
It doesn’t seem like there’s much to see, but there are some colonial buildings near the docks. The most important of these buildings are the monastery of Nossa Senhora do Carmo (1593) and the church of Nossa Senhora do Conceição (1626). The former can be seen from the docks.
The city has a few favelas sprawling over the hills behind it which makes for interesting scenery. Supposedly at one time Angra dos Reis was just as beautiful of a colonial city as Paraty, but the encroachment of the favelas have destroyed most of the historical treasures.