Along the East coast of the UK, there were originally 29 Martello towers built, between 1808 and 1812.  
These towers stretched between St Osyth in Essex and Aldeburgh in Suffolk,  and originally there were 11 in Essex and 18 in Suffolk.

Martello Tower R Felixstowe

Tower R is now built into what was Bartlett Hospital above Undercliff Road East in Felixstowe. The hospital closed in 2006 and was converted into flats in 2013. The tower was built with a moat and glacis. It was thought lost for a long period of time but does survive to the height of the glacis wall having been slighted and subsequently used as the Boiler room underneath what was the the Bartlett Hospital.

Martello Tower R  (front)

Martello Tower R  (front)

The tower itself has lost its outer brick skin and has been partially rendered, the condition of the tower is generally good although the chance of many original features surviving seems very remote.
Most of the original land holding may be disentangled from more recent development and the boundary seems to have been preserved over three quarters of its length. 

The surviving portion of the tower appears to be around half the full height of the tower, with brickwork which is still in good condition and the moat and glacis are both equally well preserved.

  Historic England Listing

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Tower L, Shotley Point, Suffolk, (NGR:TM 2483 3366, scheduled and grade II listed) was not
visited as it was impossible to gain access to the former HMS Ganges site.This tower was built with
a moat and glacis although previous work has noted that these have been filled-in. From a distance
the tower appears to be derelict but in good overall condition.Work carried out by Suffolk County
Council in 2000 noted that there appears to be the remains of the forward battery still surviving.
The area of the battery associated with Tower L is recommended for further investigation … [as
there are] some suggestions that parts of the battery might still survive (Breen & Sommers 2002,
13-5).There appear to still be traces of the land parcel boundary surviving in modern maps of this
area.
Tower M, Shotley Point, Suffolk, (NGR:TM 2513 3415, scheduled and grade II listed) was not
built to support a forward battery and was built without a ditch. It was not possible to get close
to this tower as access proved impossible to the former HMS Ganges.The tower could be seen
from the marina,which showed that the tower is in poor condition with large vertical cracks in the
brickwork, this may be as a result of the extra pressure on the building because of the water tank
on the roof. It was noted that the tower appeared to be leaning slightly, which shows the extreme
pressures which its fabric must be under. Part of the original boundary can still be perceived on
modern maps of the site.
Towers L and M are both associated with the defence of the Shotley peninsula, there were two
associated batteries and the area was re-fortified in the 1860s, in the 20th century the site had
many training buildings constructed for the Royal Navy and the fortifications were neglected
(Aitkens 2003, 2-3)
The “Old Battery”, Shotley Point, Suffolk, marked on a plan from the 1860s is no longer
tracable; it was situated on the seaward side of the marina roughly