Most colleges charge, understandably (but --), for admittance, but we found three that don't and they all had quads, gardens and chapels worth seeing.
Pembroke has particularly appealing gardens and its chapel was the first building of Sir Christopher Wren, later architect of St Paul's Cathedral in London.
Peterhouse and Trinity Hall also provided us with real pleasure and it would be nice to think there will always be somewhere in Cambridge that doesn't empty the pocket.