They were somewhat spooked by them actually, and Saxon settlements tended to be at a distance from them. They didn't re inhabit the old City of London inside the Roman walls but set up their new town in Aldwych (i.e. "new town") to the west.
Here's the fragments of an early Saxon poem where a Saxon talks about (allegedly) the baths at Aquae Sulis/Bath.
faculty.arts.ubc.ca/sechard/oeruin.htm
Battlements broken, giant’s work shattered.
Roofs are in ruin, towers destroyed,
Broken the barred gate, rime on the plaster,
walls gape, torn up, destroyed,
consumed by age. Earth-grip holds
the proud builders, departed, long lost,
and the hard grasp of the grave, until a hundred generations
of people have passed. Often this wall outlasted,
hoary with lichen, red-stained, withstanding the storm,
one reign after another; the high arch has now fallen.
The wall-stone still stands, hacked by weapons,
by grim-ground files.
Mood quickened mind, and the mason,
skilled in round-building, bound the wall-base,
wondrously with iron.
Bright were the halls, many the baths,
High the gables, great the joyful noise,
many the mead-hall full of pleasures.
Until fate the mighty overturned it all.
Slaughter spread wide, pestilence arose,
and death took all those brave men away.
Their bulwarks were broken, their halls laid waste,
the cities crumbled, those who would repair it
laid in the earth. And so these halls are empty,
and the curved arch sheds its tiles,
torn from the roof. Decay has brought it down,
broken it to rubble. Where once many a warrior,
high of heart, gold-bright, gleaming in splendour,
proud and wine-flushed, shone in armour,
looked on a treasure of silver, on precious gems,
on riches of pearl...
in that bright city of broad rule.
Stone courts once stood there, and hot streams gushed forth,
wide floods of water, surrounded by a wall,
in its bright bosom, there where the baths were,
hot in the middle.
Hot streams ran over hoary stone
into the ring