The A1213 is one of only two classified north-south roads in the City of London, the other being the A201 to the west. Many classified roads in the City lost their number in the late 20th century. Whereas the A1213 did not, some of the roads surrounding it did, so both ends are now in arbitrary positions, which made sense before this declassification.
The road starts at traffic lights in the shadow of Tower 42 on the A10 Bishopsgate. That road used to turn right here into Threadneedle Street to end at the Bank - but that is now unclassified ans so the road just morphs into the A1213. It heads south along the remainder of Bishopsgate to the next set of traffic lights, where it used to cross the A11.
Now on Gracechurch Street the road passes Leadenhall Market and meets the western end of Fenchurch Street, formerly the A1212. The Monument then becomes visible and the A1213 bears right in its shadow at traffic lights on Eastcheap, which used to be the A100. The road ends a few yards further on at the next set of lights, where it meets the A3 King William Street, which is now only classified to the left. The road ahead, Cannon Street, used to be the A4.