Firstly you will need to understand the picture below.
The initial location on North Terrace is a clue and is where a certain well off toff needed to pay back a huge debt, so he did in the form of marble.
Working with the only symbol from the diagram that can be represented like this: abcd-efgh=ij, you will find the cache at: S34 54.gb(a+i) E138 34.f(c+e)b
The cache container is greenish, and is next to a green.
Vtaber gur wcrt negrsnpgf, vg'f gur cnggrea lbh unir gb jbex bhg. N cnggrea sebz 2006.
Vf gung ernyyl n zvahf fvta?
Lbh ner nyy erfcbafvoyr sbe gur vzntr...rkprcg gur xvqf, gurl'er gbb lbhat.
Jvyy gur Terraf rire or cneg bs guvf?