The exhaust system starts with the exhaust manifold, no longer cast iron but compressed steel, obviously much lighter but will it last the life of the car as did its predecessor. You also clearly see the upstream 02 sensor which is actually located in the manifold which is bolted to the engine at this point.
Removing the exhaust manifold complete will not be easy due to its location where space is at a premium. Should The 02 sensor fail this likewise will not be easy to get at being just forward of the plugs, as far as I can see only a ring spanner will do the job as the connector on the cable of the O2 sensor will not pass through the neck of a socket.
Just to the rear and forming part of the manifold is a small cylinder obviously forming part of the emissions control on this model.
Just to the rear of that cylinder is another cylinder which at this point seems to be all part of the manifold /catalytic converter assembly. The down stream O2 sensor can also be seen fitted into the larger cylinder
This makes me believe that the exhaust manifold includes the two forward boxes plus the manifold itself.
This photo is taken looking towards the back of the car , the silencer can be seen with a clamped joint between these two units.
The silencer is supported by a 25mm wide band under which is the silencer support bracket is located, this is the same method which was employed on the W168 A Class and in my opinion is the weakest point on the exhaust system, it is well worth while keeping this band painted with high temperature paint which will keep out the rust which is what causes it to fail. As can be seen early stages of rusting is already forming between the band and the silencer on my car this will be cleaned off and painted in a few days. Spray can of High temperature paint as used on exhaust manifolds or brake callipers is ideal and makes the job easier.
The support band is supported by two rubber support s the red one being on the inside. It is important to check these prior to an MOT as any missing or broken supports will cause the car to fail the test.
This shows the rear exhaust hanger, which is of the same design as the W168, only 5/10 for the welding of the hanger onto the exhaust, pretty poor on a vehicle of this quality.
These rubber hangers are more easily fitted if a small amount of grease is applied to the metal support before fitting, excess is easily wiped off .
Should you wish to add that little extra to your vehicle then you can purchase a stainless steel tail pipe enhancer is very easy to fit and which in my opinion takes of the blandness off the original tailpipe.
The brochures for the 'A' Class, W169 show the classic and classic SE models as having a round tail pipe however this classic SE has an oval pipe , the exhaust is obviously the original factory installed unit .So us your VIN when buying spares or you may finish up with something different to that which is fitted.
The support band is supported by two rubber support s the red one being on the inside. 
The brochures for the 'A' Class, W169 show the classic and classic SE models as having a round tail pipe however this classic SE has an oval pipe , the exhaust is obviously the original factory installed unit .So us your VIN when buying spares or you may finish up with something different to that which is fitted.