It's coming up soon, from the 9th September to the 18th.
The theme this year is Traditions, Myths and Legends.
The Hay History Group are involved, offering free Hay Tours (a Heritage Walk) on Saturday 17th September (donations welcome). Numbers are limited, so they ask that people who want to go on the tours book online at www.Hayhistorygroup.co.uk
The Hay Model Railway will also be open at Salem Chapel, for £1 entry.
And in the evening there's a talk at Cusop Village Hall from 7pm, entitled The Landscape History around Hay, from the Earliest Times to the Norman Conquest. The speaker is Bill Britnell, from the Clwyd-Powys Archaeological Trust (I used to work for them, in the dim and distant past!) The talk costs £4, including tea or coffee, and again, they ask people who want to go to book online.
There will be more Hay Tours on Sunday 18th September, including an Armstrong the Poisoner Walk - again, they are free, but need to be booked online.
At the same time, there will be several archaeological digs going on in several gardens round town and at Hay Castle, overseen by Peter Dorling, the archaeolgist at Hay Castle.
The Castle will also be the site of a pop-up museum which will include a display by Eric and Tim Pugh, information about local archaeology, the Hay Wells Project and the Richard Booth Exhibition. That's free from 12noon to 4pm. From 3pm Mari Fforde will be giving a talk (also free) on the Hay Castle Project.
Hay also has a Railway Tour, following a three mile long flat route which includes a portion on the Warren, and the Eliza Trail, which is a self-guided walk aimed at children and families, starting and finishing at Hay Cheesemarket. While chasing her lost dog around town, Eliza follows a trail that reveals some interesting facts about Hay's history - the Tourist Information Bureau has details of the walk.
Meanwhile, in Brecon, the cathedral tower will be open to the public on Friday 9th September. I've been invited to join friends on this tour, as someone dropped out and there was a spare ticket. There are three tours throughout the day, at 9.45am, 10.45am and 11.45am, with dire warnings that the tower was not built for tourists and photographers, and anyone over five feet tall must wear a hard hat! And sensible shoes. And don't do it if you have heart or lung problems! The tickets cost £5, and can be booked through the Cathedral Office on 01874 623857 or email@example.com
Elsewhere around Brecknock, there are presentations and display stands at Studio at Theatr Brycheiniog on the 9th September, from 7.30pm, admission free, and a week long display at Brecon Library put on by Breconshire Local and Family History Society. There are walks around Llangynidr, Llywel and Llanddew. Powys Archives will be open for researchers on Thursday and Friday, Robin Williams will be giving a talk about the Tramroads of Brynmawr for the Crickhowell and District History Society, Llanhamlach Church will be open, and Llanwrtyd Heritage and Arts Centre will have a display on local Eistddfodau in the Victorian and Edwardian eras.
Brecknock History Forum, who are organising the week of events, can be reached on firstname.lastname@example.org for more information.