Vehicles!

The young men like all sorts of vehicles. Here we've got the Red Line (double tracked, with several cross-over switches and a station that Alex proclaimed to be MIT), Lightning McQueen and his buddies in a tight formation, and a Duplo destroyer with a helicopter deck and hangar, a boat, and a deck gun that launches little darts. Alex set up the first two, but the destroyer was constructed by the oldest young man. Photos here.