The C104 comprises two parallel streets in the centre of Lerwick. The longer of the two is the C104-005, King Harald Street, which meets the A969 at each end, and passes the B9072 in the middle. This is the former line of the A970 through Lerwick, and is sometimes shown on maps as part of the B9072, although this does not appear to be the case.
The second part of the C104 is Market Street, labelled the C104-130, which lies further to the east. This runs south from the A969, crosses the B9072, and comes to an end by the police station and county buildings. The C105 continues to the right along Hillhead.