It is crazy how Kharkiv has held out - close to the border opposite several big Russian military bases which Russia had beefed up the transport network to, long way from the Ukrainian supply lines, facing off against a force primarily composed of elements from 3 of Russia's elite divisions with heavy armour and combat experience rather than the likes of VDV and forces fleshed out with conscripts, militia or contractors etc.
At one point the defenders were on the back foot when a Russian column made what seems to be an accidental run into the city centre, but they were repulsed.