At the start of the long dual track descent that starts after the cuttings north of Huntingdon, you pass Abbots Ripton, which is the site of the fatal Flying Scotsman crash of 1876 in a blizzard, and where the weight of snow prevented a signal arm rising to 'on' to protect a preceeding goods train which was reversing into a siding. (Signalling was changed forever after that.)
The site is just before the lonely St Andrews Church standing in fields at Woodwalton, on the east side.
Before Peterborough, just after the football ground on the east side, you cross the line from Ely on a lattice girder bridge. On the west side the Peterborough statin of the Nene Valley Railway can just be seen, . . . .
It is worth noting that the 'jump' up onto that bridge is the steepest gradient on the ECML between London and Edinburgh*. It's only a couple of hundred meters at 1 in 100, but it is remarkable in shifting from going under a road bridge to over another road in such a short distance (both roads being at similar heights).
* [I say steepest
between London and Edinburgh, as I believe the short drop out of Kings Cross to get under the canal may be steeper, and the corresponding climb into Waverley from Calton tunnel is definitely steeper]
Other points of rail interest between Peterborough and Grantham include:
a six-track railway over Helpston LC, before the line to Stamford, Oakham and Leicester veers off to the west;
remnants of an east-west railway bridge at Essendine (with spans off to the east side towards Bourne);
remnants of another east-west railway bridge at Little Bytham (Leicester - Melton - Spalding);
the site of the first 100mph speed record by the Flying Scotsman in 1934 , also at Little Bytham (and which unlike the Mallard record, does not have a commemorative sign)
Much further north, just as the right-left-right-left-right curves before Retford begin at Tuxford, there is the recently re-opened line into Marnham colliery on a bridge over the ECML.
There is a thing of wonder and beauty just before Finsbury Park on the eastern side of the ECML as you head north, it's called the Emirates Stadium.
To my mind, 'a thing of beauty and wonder' right there is on the other side of the track: its Sarah Wrigglesworth's eco house, "
The Straw House" which stands on stilts next to the ECML, insulated with straw bales and quilting, and which includes an observation tower.